When it comes to AR-15 magazines, you want one that will work flawlessly every time no matter what conditions you find yourself in. The Magpul PMAG 40 GEN M3 is a 40 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. The M3 magazines have modified internal and external geometry which also permits operation with a wide range of non Colt-spec platforms such as the HK 416 and MR556A1, M27 IAR, British SA-80, FN SCAR MK 16/16S, and others. A redesigned bolt catch notch in the rear of the magazine provides increased bolt catch clearance, while an over-travel stop on the spine helps ensure the magazine will not over-insert on compatible weapons.