The GLOCK 21 Gen4 Gray frame in 45 AUTO, makes big design changes to the pistol that has found worldwide adoption with security services both public and private. The new modular back strap system allows you to quickly customize its grip to adapt to an individual’s hand size. The frame surface uses the newly designed, real world tested, Gen4 rough textured technology (RTF). The new GLOCK dual recoil spring assembly substantially increases the life of the firearm, all while drastically reducing recoil. A reversible enlarged magazine release can be changed in seconds, and it accommodates both left and right-handed shooters. The GLOCK 21 Gen4 Gray frame in 45 AUTO retains the GLOCK accessory rail for attachments of your choice.