Remarkable for its accuracy and light recoil, the Glock 21 Gen 4 delivers the legendary stopping power of the 45 ACP round with a higher magazine capacity. The modular back strap design on the G21 Gen 4 lets you instantly customize the grip to adapt to an individual shooter's hand size. Its frame employs the scientifically designed, real-world-tested, Gen 4 rough textured technology. Internally, the Glock dual recoil spring assembly substantially increases the life of the system. A reversible enlarged magazine catch, changeable in seconds, accommodates left or right-handed operators. Ships with three 10RD magazines.