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Posted: 5/13/2015 12:07:40 AM EDT
[#1]
Quoted:
How come they exist? Is there reason back in history that the commercial tube held some advantage in production, etc? Like the tube diameter was a standard dimension for some other purpose and industry decided to use it to save $$ or what? Anybody know? BLUF: They're cheaper. The original commercial receiver extensions had threads that were cut into an extrusion, vice the rolled threads that sit proud of the tube's surface on a standard receiver extension. Because of this production method - to fit the same threaded hole in the receiver, commercial receiver extensions needed to be slightly larger in overall diameter, to match the threading in the receiver. Hence, the "commercial spec" receiver extension and stock were born. 
~Augee |
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Posted: 5/13/2015 12:25:49 AM EDT
[#2]
Ah Ha!!
THANKS and very interesting. Augee; do you know what maker introduced the commercial tube/extension and when? |
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Posted: 5/13/2015 12:34:04 AM EDT
[#3]
Quote HistoryQuoted:
Ah Ha!! THANKS and very interesting. Augee; do you know what maker introduced the commercial tube/extension and when? Not authoritatively - however, if I were to guess, I would say likely in the 1980s, as the SP1 was introduced in the late-70s ('77-78), and probably by one variation or another of Jerry Drasen's companies (Nesard, Sendra, Drasen). ~Augee |
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Posted: 5/13/2015 12:42:28 AM EDT
[#4]
Quote HistoryQuoted:
Not authoritatively - however, if I were to guess, I would say likely in the 1980s, as the SP1 was introduced in the late-70s ('77-78), and probably by one variation or another of Jerry Drasen's companies (Nesard, Sendra, Drasen). ~Augee Quote HistoryQuoted:
Quoted:
Ah Ha!! THANKS and very interesting. Augee; do you know what maker introduced the commercial tube/extension and when? Not authoritatively - however, if I were to guess, I would say likely in the 1980s, as the SP1 was introduced in the late-70s ('77-78), and probably by one variation or another of Jerry Drasen's companies (Nesard, Sendra, Drasen). ~Augee Do you mean that the SP1 uses the commercial tube? So maybe did Colt originate the design? |
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Posted: 5/13/2015 12:53:52 AM EDT
[#5]
It was Frank Zappa; he was strictly commercial.
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Posted: 5/13/2015 12:57:33 AM EDT
[#6]
Quote HistoryQuoted:
It was Frank Zappa; he was strictly commercial. I don't know him, but he can go to hell for making those things. The world would be a better place without commercial receiver extensions. |
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Posted: 5/13/2015 1:02:17 AM EDT
[#7]
Quote HistoryQuoted:
Do you mean that the SP1 uses the commercial tube? So maybe did Colt originate the design? No, no, The R6001 SP1 Carbine used a standard, two position receiver extension. That receiver extension had been in service since 1966, though, on the Colt R609/10, the XM177 and XM177E1 SMGs in Vietnam. Prior to that, with the R607, Colt used a totally different two position stock design that was much more difficult to manufacture, and not as durable. I mentioned the SP1 Carbine, and its introduction date only because I'm speculating that the biggest "demand" for an aftermarket telescoping stock would have been after Colt released their first carbine for commercial sales, and it became the "gotta have" new part, leading to the aftermarket responding. ~Augee |
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Posted: 5/13/2015 7:08:50 AM EDT
[#8]
Quote HistoryQuoted:
BLUF: They're cheaper. The original commercial receiver extensions had threads that were cut into an extrusion, vice the rolled threads that sit proud of the tube's surface on a standard receiver extension. Because of this production method - to fit the same threaded hole in the receiver, commercial receiver extensions needed to be slightly larger in overall diameter, to match the threading in the receiver. Hence, the "commercial spec" receiver extension and stock were born. http://img.photobucket.com/albums/v668/NotDeaf/buffertubescivmil.jpg http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg http://i282.photobucket.com/albums/kk259/DRisThor/Thread%20Gun%20Pics/Milspecvscommercial.gif ~Augee Quote HistoryQuoted:
Quoted:
How come they exist? Is there reason back in history that the commercial tube held some advantage in production, etc? Like the tube diameter was a standard dimension for some other purpose and industry decided to use it to save $$ or what? Anybody know? BLUF: They're cheaper. The original commercial receiver extensions had threads that were cut into an extrusion, vice the rolled threads that sit proud of the tube's surface on a standard receiver extension. Because of this production method - to fit the same threaded hole in the receiver, commercial receiver extensions needed to be slightly larger in overall diameter, to match the threading in the receiver. Hence, the "commercial spec" receiver extension and stock were born. http://img.photobucket.com/albums/v668/NotDeaf/buffertubescivmil.jpg http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg http://i282.photobucket.com/albums/kk259/DRisThor/Thread%20Gun%20Pics/Milspecvscommercial.gif ~Augee There are mil-spec diameter tubes with cut threads. You just make the thread area fatter. Cut threads are not as strong as rolled threads, but making a fat thread area it is just as easy to make what you have described. EDIT: Below is what a cut thread, Mil-Spec receiver extension looks like. You may note that at the end of the fat portion the threads continue. 
The only reason to make the actual tube larger is if you did not want military stocks to fit on the receiver extension. I think it comes from the same sort of reasoning that brought about oversized pivot and takedown pins. |
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Posted: 5/13/2015 8:05:27 AM EDT
[#9]
Quote HistoryQuoted:
It was Frank Zappa/Furtrapper;WHO he was strictly FROMcommercial. FIFY |
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Posted: 5/13/2015 9:19:04 AM EDT
[#10]
Quote HistoryQuoted:
No, no, The R6001 SP1 Carbine used a standard, two position receiver extension. That receiver extension had been in service since 1966, though, on the Colt R609/10, the XM177 and XM177E1 SMGs in Vietnam. Prior to that, with the R607, Colt used a totally different two position stock design that was much more difficult to manufacture, and not as durable. I mentioned the SP1 Carbine, and its introduction date only because I'm speculating that the biggest "demand" for an aftermarket telescoping stock would have been after Colt released their first carbine for commercial sales, and it became the "gotta have" new part, leading to the aftermarket responding. ~Augee Quote HistoryQuoted:
Quoted:
Do you mean that the SP1 uses the commercial tube? So maybe did Colt originate the design? No, no, The R6001 SP1 Carbine used a standard, two position receiver extension. That receiver extension had been in service since 1966, though, on the Colt R609/10, the XM177 and XM177E1 SMGs in Vietnam. Prior to that, with the R607, Colt used a totally different two position stock design that was much more difficult to manufacture, and not as durable. I mentioned the SP1 Carbine, and its introduction date only because I'm speculating that the biggest "demand" for an aftermarket telescoping stock would have been after Colt released their first carbine for commercial sales, and it became the "gotta have" new part, leading to the aftermarket responding. ~Augee Oh, OK. That makes more sense. I didn't think the SP1 used a commercial extension so I was confused. It would be an interesting tidbit to know who started it because when it was first rolled out, naturally stocks and whatnot were not available en masse to accommodate the then new extension. I'd be curious to know sort of how the companies lined up in production, ie. who first then who followed. |
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Posted: 5/13/2015 10:11:37 AM EDT
[#11]
They exist beause they are cheaper to produce and manufacturers know $ is big factor for civilians whereas the military usually ignores cost and focuses on performance and quality. There's really nothing wrong with a com buffer tube, not like it's going to explode or anything. With that being said I prefer the mil spec tube, it's short and lighter than the commercial tube.
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Posted: 5/13/2015 10:26:13 AM EDT
[#12]
I was told in an armorer's school it had to do with the definition of military weapon parts and their shipping. The commercial tubes did not meet the technical definition and allowed them to be shipped to places that you could not ordinarily ship them.
I have never investigated this. I am not claiming it is the absolute correct response. But the guy that taught it is a very in the know person. |
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Posted: 5/13/2015 10:57:55 AM EDT
[#13]
I'll add this:
If the material is unkown, the thicker commercial tube is the better bet. True mil spec tubes are 7075 aluminum, but there are a lot of mil spec diameter tubes that are 6061 extrusions. The latter are much weaker than their 6061 commercial diameter counterparts. |
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Posted: 5/13/2015 11:00:01 AM EDT
[#14]
Quote HistoryQuoted: I was told in an armorer's school it had to do with the definition of military weapon parts and their shipping. The commercial tubes did not meet the technical definition and allowed them to be shipped to places that you could not ordinarily ship them. I have never investigated this. I am not claiming it is the absolute correct response. But the guy that taught it is a very in the know person. I've been involved in manufacturing large numbers of the receiver extensions, mil-spec extensions are much easier to make, any cost increase of mil-spec vs commercial spec tubes is from the alloy used 7075 vs 6061 and the additional finishing requirements for the mil-spec extension (the difficult to apply correctly down in a deep hole dry film lube). |
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Posted: 5/13/2015 11:33:12 AM EDT
[#15]
Quote HistoryQuoted:
I suspect this is closer to the truth than any other idea out there. Quote HistoryQuoted:
Quoted:
I was told in an armorer's school it had to do with the definition of military weapon parts and their shipping. The commercial tubes did not meet the technical definition and allowed them to be shipped to places that you could not ordinarily ship them. I have never investigated this. I am not claiming it is the absolute correct response. But the guy that taught it is a very in the know person. NO. ITAR rules apply to any weapon or part of a weapon, or any weapon accessory, that can be used in the waging of war, whether they be commercial, or military in origin. As far as export laws go, Commercial or Mil-Spec, it doesn't go outside the country without a note from the State Department.... Also, the shape of a commercial tube, with the large radii at the key are easier to extrude than the Mil-Spec. |
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Posted: 5/13/2015 11:50:42 AM EDT
[#16]
The other thing that everyone is missing is the fact that milspec calls for 7075. That cannot be welded, therefore the entire thing must be cut from a single piece of Al, thus making it a completely machined part. With 6061 being weldable the tube can be just an Al tube, cut to the right length, weld an end on it, weld on a rail for the lockstops for your adjustable stock, and voila, much cheaper and easier to produce. It's not necessarily THAT inferior, but I find it less desirable.
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Posted: 5/13/2015 12:10:21 PM EDT
[#17]
Quote HistoryQuoted: NO. ITAR rules apply to any weapon or part of a weapon, or any weapon accessory, that can be used in the waging of war, whether they be commercial, or military in origin. As far as export laws go, Commercial or Mil-Spec, it doesn't go outside the country without a note from the State Department.... Also, the shape of a commercial tube, with the large radii at the key are easier to extrude than the Mil-Spec. Quote HistoryQuoted: Quoted: Quoted: I was told in an armorer's school it had to do with the definition of military weapon parts and their shipping. The commercial tubes did not meet the technical definition and allowed them to be shipped to places that you could not ordinarily ship them. I have never investigated this. I am not claiming it is the absolute correct response. But the guy that taught it is a very in the know person. NO. ITAR rules apply to any weapon or part of a weapon, or any weapon accessory, that can be used in the waging of war, whether they be commercial, or military in origin. As far as export laws go, Commercial or Mil-Spec, it doesn't go outside the country without a note from the State Department.... Also, the shape of a commercial tube, with the large radii at the key are easier to extrude than the Mil-Spec. |
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Posted: 5/13/2015 12:16:11 PM EDT
[#18]
Quote HistoryQuoted:
... probably by one variation or another of Jerry Drasen's companies (Nesard, Sendra, Drasen). For the vast majority that dont remember the 1980s aftermarket scene, companies like Nesard made AR parts available for cheap, very cheap, like $275 for a rifle/carbine kit minus the receiver. I had the opportunity to build my first AR on a Nesard kit using an Essential Arms lower. What a steaming POS that thing was. I look back on it as a great learning experience because I had to troubleshoot and replace nearly every part because they were all made so cheaply and out of any sort of spec. Examples: stamped disconnector that wasn't even hardend and over 50% of the engagement surface was reduced due to the stamping effect on the part, causing hammer follow strings randomly. Plastic delta slip ring that broke, bolt broke on 5th shot at cam pin hole, hammer pin broke inside of 100 rounds, non staked or even tourqued properly gas key bolts that loosened and got the gas key and gas tube chewed up quickly. Rifle length recoil spring cut down for collapsible stock RE, the actual RE was not only commercial spec it was welded together and the end cap made the internal length too short causing cycling issues, Hell even the FSB looked like it was cast in playground sand - it was pockmarked deeply over its entire surface. If anybody had anything to do with starting cheap ass outa spec parts I'd bet a dollar it started with Nesard 
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Posted: 5/13/2015 12:40:36 PM EDT
[#19]
Topic Moved
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Posted: 5/13/2015 12:45:37 PM EDT
[#20]
Today, it's really important to pay attention to what you're getting. If it's "MIL-SPEC," it needs to be made from 7000-series aluminum, be the proper outside diameter, and have rolled threads. If it's "mil-spec sized," it can be made from anything, and have any kind of threads just so long as it has the proper outside diameter.
There are plenty of pictures out there stating that "commercial tubes have angled backs." Some do, some don't. You have to measure the OD to see what sort of stock will fit that tube. And a "true MIL-SPEC" extension may have only 4 positions for the stock locking pin, rather than 6 on most extensions. |
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Posted: 5/13/2015 12:54:24 PM EDT
[#21]
Quote HistoryQuoted: NO. ITAR rules apply to any weapon or part of a weapon, or any weapon accessory, that can be used in the waging of war, whether they be commercial, or military in origin. As far as export laws go, Commercial or Mil-Spec, it doesn't go outside the country without a note from the State Department.... Also, the shape of a commercial tube, with the large radii at the key are easier to extrude than the Mil-Spec. Quote HistoryQuoted: Quoted: Quoted: I was told in an armorer's school it had to do with the definition of military weapon parts and their shipping. The commercial tubes did not meet the technical definition and allowed them to be shipped to places that you could not ordinarily ship them. I have never investigated this. I am not claiming it is the absolute correct response. But the guy that taught it is a very in the know person. NO. ITAR rules apply to any weapon or part of a weapon, or any weapon accessory, that can be used in the waging of war, whether they be commercial, or military in origin. As far as export laws go, Commercial or Mil-Spec, it doesn't go outside the country without a note from the State Department.... Also, the shape of a commercial tube, with the large radii at the key are easier to extrude than the Mil-Spec. Mil-spec tubes are not extruded like most commercial tubes, that's where most of the geometry difference comes from. The OD and wall thickness of commercial tubes is what it is to provide for the correct major diameter of the threads, the impact extrusion process used for the mil-spec receiver extensions allows for the extension to be extruded with a larger OD in the threaded area (it also allows for the extrusion/forging to be partially hollow saving a ton of material and machine time). Something that always bugged me though is I've never found any evidence for the idea that the threads are rolled or have ever been rolled, other than internet hearsay. The current mil-spec certainly does not require or mention it and I've never seen any old prints mentioning it either. Not to say it never was done this way, but with the availability of 4 axis machining centers it would not make any sense to roll form the threads unless the specifications required it. |
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Posted: 5/13/2015 1:27:58 PM EDT
[#22]
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Posted: 5/21/2015 1:55:56 AM EDT
[#23]
Quote HistoryQuoted:
The only reason to make the actual tube larger is if you did not want military stocks to fit on the receiver extension. I think it comes from the same sort of reasoning that brought about oversized pivot and takedown pins. Depending on how you're making them it can also result in needing fewer steps and less removed material. They're simply cheaper to make. |
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Posted: 5/21/2015 9:10:45 AM EDT
[#24]
Just looking at the threads on a real MIL-SPEC receiver extension will show you that they are not cut. There is only one other way to get such threads - rolling. Rolling is a forging-like process (almost all commercial bolts are roll-threaded, it's quicker and cheaper, but it's also stronger), which makes threads that stand out from the base material. I don't have access to the specific MIL-SPEC for the receiver extension, but as I said, the only practical way to make those threads is by rolling. I hope someone with access to TDP information can chime in on this to say what exactly the spec is, but I can't see it being anything but rolled threads.
Others have mentioned (not just here) that some commercial-size tubes are "extruded just like MIL-SPEC." This is not entirely accurate. A commercial extension may be extruded (rather than drawn, which is how I think the earliest ones were made), but the process for MIL-SPEC extensions is "impact extrusion." Regular extrusion of this sort of part consists of just pushing a mandrel into an aluminum blank to push it into a die, shaping the raw part. Impact extrusion, on the other hand, "hammers" the blank into the die. This is a forging process, and forging (like with receivers) makes a part that is stronger than just billet material because the forged blank's metal crystal structure is shaped by the forging process. |
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Posted: 5/21/2015 9:49:14 AM EDT
[#25]
Quote HistoryQuoted: Just looking at the threads on a real MIL-SPEC receiver extension will show you that they are not cut. There is only one other way to get such threads - rolling. Rolling is a forging-like process (almost all commercial bolts are roll-threaded, it's quicker and cheaper, but it's also stronger), which makes threads that stand out from the base material. I don't have access to the specific MIL-SPEC for the receiver extension, but as I said, the only practical way to make those threads is by rolling. I hope someone with access to TDP information can chime in on this to say what exactly the spec is, but I can't see it being anything but rolled threads. Others have mentioned (not just here) that some commercial-size tubes are "extruded just like MIL-SPEC." This is not entirely accurate. A commercial extension may be extruded (rather than drawn, which is how I think the earliest ones were made), but the process for MIL-SPEC extensions is "impact extrusion." Regular extrusion of this sort of part consists of just pushing a mandrel into an aluminum blank to push it into a die, shaping the raw part. Impact extrusion, on the other hand, "hammers" the blank into the die. This is a forging process, and forging (like with receivers) makes a part that is stronger than just billet material because the forged blank's metal crystal structure is shaped by the forging process. I'll post a few pictures of a raw impact extrusion this evening. |
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Posted: 5/21/2015 11:50:51 AM EDT
[#26]
Remember that the raw impact extrusion is indeed "raw," and will be machined down to the required OD, just as the ID will be machined. Sure, the CNC program could leave the thread area quite tall, allowing for cut threading, but the "best practice" for such cut threading would be on a lathe, right? On the other hand, rolled threads could be done on a piece that was already pretty much at finished OD, and can be done without with a die system. Cut threads also weaken material, while rolled threads displace material, cold working the metal, retaining the tube thickness beneath the threads, and producing a stronger piece of work.
I wish I could quote an authoritative reference on this, but I'm pretty darn sure that actual MIL-SPEC (i.e. made to TDP requirements) receiver extensions have rolled threads. |
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Posted: 5/21/2015 1:09:28 PM EDT
[#27]
the forum is doing that thing again...
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Posted: 5/21/2015 1:19:55 PM EDT
[#28]
Quote HistoryQuoted: Remember that the raw impact extrusion is indeed "raw," and will be machined down to the required OD, just as the ID will be machined. Sure, the CNC program could leave the thread area quite tall, allowing for cut threading, but the "best practice" for such cut threading would be on a lathe, right? On the other hand, rolled threads could be done on a piece that was already pretty much at finished OD, and can be done without with a die system. Cut threads also weaken material, while rolled threads displace material, cold working the metal, retaining the tube thickness beneath the threads, and producing a stronger piece of work. I wish I could quote an authoritative reference on this, but I'm pretty darn sure that actual MIL-SPEC (i.e. made to TDP requirements) receiver extensions have rolled threads. There is no requirement for rolled threads, and I'm not sure how easy it would be roll the threads without crushing the tube, rolled threads are typically used on solid bolts and rods not tubes. It's trivial to use a CNC mill to produce effectively perfect threads on the tube, it also helps to insure the threads are cut concentric to the bore and the extrusion itself by doing all the machining in a single operation. |
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Posted: 5/21/2015 1:35:09 PM EDT
[#29]
Quote HistoryQuoted:
There is no requirement for rolled threads, and I'm not sure how easy it would be roll the threads without crushing the tube, rolled threads are typically used on solid bolts and rods not tubes. It's trivial to use a CNC mill to produce effectively perfect threads on the tube, it also helps to insure the threads are cut concentric to the bore and the extrusion itself by doing all the machining in a single operation. Quote HistoryQuoted:
Quoted:
Remember that the raw impact extrusion is indeed "raw," and will be machined down to the required OD, just as the ID will be machined. Sure, the CNC program could leave the thread area quite tall, allowing for cut threading, but the "best practice" for such cut threading would be on a lathe, right? On the other hand, rolled threads could be done on a piece that was already pretty much at finished OD, and can be done without with a die system. Cut threads also weaken material, while rolled threads displace material, cold working the metal, retaining the tube thickness beneath the threads, and producing a stronger piece of work. I wish I could quote an authoritative reference on this, but I'm pretty darn sure that actual MIL-SPEC (i.e. made to TDP requirements) receiver extensions have rolled threads. There is no requirement for rolled threads, and I'm not sure how easy it would be roll the threads without crushing the tube, rolled threads are typically used on solid bolts and rods not tubes. It's trivial to use a CNC mill to produce effectively perfect threads on the tube, it also helps to insure the threads are cut concentric to the bore and the extrusion itself by doing all the machining in a single operation. Thanks. A confusing topic to be sure. I do not know a whole lot about manufacturing but I do work with metals in knifemaking and I was going to ask about this. Are threads rolled on the aluminum tube or not? I see your point here and find it hard to believe they would be. Can anyone give a step by step as to how both civvy and milspec tubes are made? Thanks and a very interesting topic. |
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Posted: 5/21/2015 2:32:03 PM EDT
[#30]
Quote HistoryQuoted: Thanks. A confusing topic to be sure. I do not know a whole lot about manufacturing but I do work with metals in knifemaking and I was going to ask about this. Are threads rolled on the aluminum tube or not? I see your point here and find it hard to believe they would be. Can anyone give a step by step as to how both civvy and milspec tubes are made? Thanks and a very interesting topic. Quote HistoryQuoted: Quoted: Quoted: Remember that the raw impact extrusion is indeed "raw," and will be machined down to the required OD, just as the ID will be machined. Sure, the CNC program could leave the thread area quite tall, allowing for cut threading, but the "best practice" for such cut threading would be on a lathe, right? On the other hand, rolled threads could be done on a piece that was already pretty much at finished OD, and can be done without with a die system. Cut threads also weaken material, while rolled threads displace material, cold working the metal, retaining the tube thickness beneath the threads, and producing a stronger piece of work. I wish I could quote an authoritative reference on this, but I'm pretty darn sure that actual MIL-SPEC (i.e. made to TDP requirements) receiver extensions have rolled threads. There is no requirement for rolled threads, and I'm not sure how easy it would be roll the threads without crushing the tube, rolled threads are typically used on solid bolts and rods not tubes. It's trivial to use a CNC mill to produce effectively perfect threads on the tube, it also helps to insure the threads are cut concentric to the bore and the extrusion itself by doing all the machining in a single operation. Thanks. A confusing topic to be sure. I do not know a whole lot about manufacturing but I do work with metals in knifemaking and I was going to ask about this. Are threads rolled on the aluminum tube or not? I see your point here and find it hard to believe they would be. Can anyone give a step by step as to how both civvy and milspec tubes are made? Thanks and a very interesting topic. |
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Posted: 5/21/2015 4:46:09 PM EDT
[#31]
I've seen a LOT of very respectable sources state the threads are rolled. To roll threads on a tube, you use a mandrel and the thread die goes around the tube. No biggie. As I said, I don't have anything authoritative, but I am firmly convinced that real, GI, made for DoD per TDP requirements receiver extensions have rolled threads.
And it's not something we'll resolve here, let alone appropriate for the OP's question. OP, commercial tubes are out there because someone could make money from them. That's it in a nutshell. Once they were out there, stock makers accommodated the different sized tube, and we have two different kinds of tubes and stocks that aren't quite interchangeable. Me? I'd stick with one type. I personally feel that any truly MIL-SPEC receiver extension, because of the more robust material, and the more robust process for making the pre-machining blanks, makes for a stronger part in any case, and while most of us will never have a chance to stress the receiver extension on one of our guns the way an M4 operator might, stronger (without being noticeably heavier, nor harder to find!) is always better in my book. |
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Posted: 5/21/2015 6:10:22 PM EDT
[#32]
Thanks.
Has there ever been on here a more or less comprehensive listing of those companies using commercial vs milspec tubes? Elsewhere? |
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Posted: 5/21/2015 7:15:25 PM EDT
[#33]
I think a better listing would be whose tubes are "actually, literally MIL-SPEC," which ones are "mil-spec diameter," and which ones are something else. That would mean lists of whose parts were the right diameter, whose were that and made from the right materials, and "everybody else."
Usually, the best advice is "go with a trusted vendor." Like BCM, for example - they're not likely to say "this is a mil-spec part," when it's made from a lesser grade of aluminum. |
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Posted: 5/21/2015 10:33:01 PM EDT
[#34]
Here's some photos of a impact extrusion used for a mil-spec receiver extension:
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Posted: 5/22/2015 9:58:35 PM EDT
[#35]
Very cool. Thanks for posting those pictures.
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