Very solidly constructed mag, no loose parts. Similar in shape to mags found on a VFC 416. Tested them out and they fit and feed in a Socom Gear PWS MK110, G&G M16a3, Classic Army Scar-L, and King Arms Sig 556 Shorty. holds 190 rounds, but I only filled mine to about the 150 round level. has a unique cup-shaped Follower that holds the round, rather than a round knob like most midcaps. definitely worth the buy.