Magpul Industries Magazine, PMAG 20 AR/M4 GEN M3, 223 Remington/556NATO, 20 Rounds, Fits AR Rifles, Black MAG560-BLK The next-generation PMAG 20 AR/M4 GEN M3 is a 20-round 5.56x45 NATO (.223 Remington) polymer magazine for AR15/M4 compatible weapons. Along with expanded feature set and compatibility" the GEN M3 incorporates new material technology and manufacturing processes for enhanced strength" durability" and reliability to exceed rigorous military performance specifications. While the GEN M3 is optimized for Colt-spec AR15/M4 platforms" modified internal and external geometry also permits operation with a range of additional weapons such as the HK(R) 416/MR556A1/M27 IAR" British SA-80" FN(R) SCAR(TM) MK 16/16S" and others.