They are for the R-4 Galil, and fit the M16 mag like it was made for it. AK mags don't fit too well, the 7.62x39's just curve too much. The flap doesn't go over too well with two mags in the pouch. The 5.45 and .223 Norinco fit better, but are sitll a tad long. The two big side pouches fit a Rubermaid 2L bottle, but it's pretty tight as well. It will carry two .75L water bottles you buy at the store though quite well. Almost like it was made for them. The top pouch on the back is too short for a Camelback, but there are shorter ones and I haven't tried anything else, as I already had the Camelback. The top back pouch also has a separate velcro flap in the top that you can run a hose, radio handset, antenna, whatever, through.
I've thought of just removing both the upper and lower back pouches and rigging it up for a removable Camelback. You could always use one of those with the carrying capability (i.e. backpack type) and it could be a pretty slick set-up.
I have two of them. One is pretty nice, so I'm leaving that as-is for .223. The other is pretty ratty in the pockets, but the harness itself is fine, so I'm going to do some experimenting with it. I'm going to switch the mag pouches to a more universal type that will take AK, M14, M16 mags. I'm going to add fastex buckles in place of the thread through straps. I'm going to take off the back pockets (which have been damaged and repaired, so no biggie there) and do the Camelback thing. I may also add the belt loops off of a junk USGI LBV I have. The 5.56 sized mag pouches off this one may migrate over to my other one, replacing some of the forward pockets, or I might make some kinda chest rig out of them.
Now, I just need a sewing machine!
Ross