Externally, what is immediately apparent is the multiple backstrap design of the frame, which can be instantly adapted to small, medium and large frame hands. The surface of the frame is the Generation 4 Rough Textured Frame. Internally, the Glock dual recoil spring assembly substantially increases the life of the system. A reversible magazine catch, changeable in seconds, accommodates left or right handed shooters. The Generation 4 frame retains the Glock accessory rail for accessory attachment.