The Chinese came out with an "improved" (or so they thought) version of the SKS in 1963. In doing so, they also adopted a more "universal" and ergonomic self-contained webbing system to go along with it. This included 6 cartridge pouches, and a 4-cell grenade pouch instead of using a chest rig and strapped grenade pouches. These are still in use today by Vietnamese Militia members as pictured, and are pretty neat pieces of gear. They will fit up to about a 44" waist as they fit me just fine. Straps are all adjustable, and it's actually a pretty comfortable set-up, yet simple.
I have found that each ammo pouch will comfortably hold 2 20 round AR mags. Wonder is that was a coincidence or planned... The world may never know.
Anyway, these are NOS 1971 dated, and are great for your collection, or for actual use.