Just received.  Typical Pathfinder high-quality Stainless steel.

Link to main vendor (Pathfinder) with pix and relevant specs (do shop around)  HERE   Many reviews on Youtube; search M-34.  Currently "on-sale" for 10% off, as are most other PF site items.

Vendor cautions about Not storing Hot liquids inside the bottle.  I suspect that the Silicone cap seal may be a little "sensitive" to heat, but a stouter seal can easily be user-made.
 
Cap is untethered; a drawback IMHO. I suspect drilling and tapping a hole in the cap would allow a short stainless steel Pan-head screw to be screwed-in (with epoxy) and maybe some "peening" of the exposed threads on bottom of screw inside the cap and a slender plastic-clad steel cable fishing leader can serve as a tether to the black nylon "bikini strap".   Another reason to replace the OEM seal with a less temp-sensitive unit.  Replacement caps are cheap and currently available from vendor.  I ordered one.

Reasonably useful size, especially if worn under outer garments during the winter to deter freezing of contents.

Original and very similar M-32 Swiss canteen+cup ensemble is still available, but usually with excessive shipping prices.  Twine string anchors bottle ,cap, and cup.  While presumably lighter (Aluminum used throughout) than the stainless steel PF M-34, the cork cap is a microbe magnet, and can dislodge, allowing contents to leak.  Aluminum bottles initially coated with an internal film to prevent deterioration of aluminum.  The film must be completely intact to prevent aluminum corrosion from contents.  If interested, check vendor return provisions.

Swiss M-84 plastic canteen + aluminum cups are less much expensive, but finding a pouch for it might be problematic.   These Pouches will fit the M-84 Swiss canteen + cup ensemble.  M-84 is much larger than the other Swiss canteens.  Carriage within outer garments even if a suitable pouch can be found, may be problematic due to bulk of larger canteen.

Obviously, M-84 plastic canteen cannot accept much heat input.  Tethered cap, and it (usually) has a gas mask adaptor.  Not sure of "types" of gas mask drinking tubes for which the Swiss M-84 cap is compatible.  USGI "gas mask" canteen cap will fit onto M-84, but I don't trust it.

Surplus pouch HERE  Fits the PF M-34 ensemble perfectly.  DO shop around.

A couple of 1" D-rings, a couple of 1" tri-glide buckles, and some Coyote Brown 1" wide webbing will allow user to rig up an adjustable shoulder strap, if desired.

Small Esbit style stove (won't fit into the pouch linked above) will allow heating of cup and/or bottle without the cap, of course., lol.

If Pathfinder would make a small slip-over stove for the cup (and bottle), a lid for the cup, and provide some sort of decent tether for the cap, this little rig would be almost perfect.  Have submitted a suggestion to PF for these improvements.  Will respond when answered.

Submitted for consideration.

Thanks. Linking the pictures in the original post instead of hotlinking them would make for a far better and more coherent presentation.

IMO, Pathfinder made a mistake by not securing the cap to the canteen with a chain to prevent loss.

You could have a small washer welded to the bottle and cap to tie it off. That should be factory done, and it kind of a deal breaker to be honest.

I understand and agree.  Unfortunately such mods will almost certainly void warranty, so I elected to buy a spare cap.

To be fair, GI "Pilot's Flask" lacks a cap tether.

Maybe simplest to paint OEM silver cap day-glo orange or similar

raf,
I've used their large mouth canteens for a few years and just tie paracord around the neck, run the line , tie a fat knot, and secure it with a small ranger band that stays tight.
The cap is easily removable if you do want to boil water in it.
Clear Pic of one of my back up sets
Attached File

Thanks for the tip!  Will take a damn small diameter Ranger Band for the M-34 cap, but it's worth investigating.

Congrats for thinking outside the box!

They make them small enough

Great idea.