The Glock 37 Gen4, in .45 G.A.P., introduces revolutionary design changes to this quantum leap forward in big-bore technology, Glock's answer to muzzle flip and high velocity recoil. The modular backstrap design lets the user adapt the grip to hand size, and the frame surface exhibits the scientifically-designed Gen4 rough textured technology. This model features a dual-recoil spring assembly that substantially increases the life of the system, and the enlarged reversible magazine catch easily accommodates left- or right-handed operators. The Generation 4 frame retains the Glock accessory rail for accessory attachment.