Magloc Competition 2 M 4S Recoil Control Thumb Rest for Glock Gen 4 and 5 Small Back Strip 1759 1. Fits Gen 4 , 5 small grip. US Patent D472,599. Reduces muzzle jump by 70% (shooting weak hand only) 2. This model does not fit Gen 1 to 3. Beaver tail length: Competition - 9mm (0.35") 3. Wings can be modified with a file to fit different hand size. 4. Avoids slide cut on web of shooting hand, increase shooting speed and accuracy 5. Youtube installation instruction: https://www.youtube.com/watch?v=8SkSyF_hefY