Gen 4 small grip Glock Competition 2 M Recoil Control Thumb Rest for Glock Gen 4 Pistol US Patent D472,599. Reduces muzzle jump by 70% (shooting weak hand only) Fits Gen 4 small grip Glock.. Beaver tail length: Competition M - 9mm (0.35") ; Duty M - 2.7mm (0.11") Increases magazine well opening by 37%. Wings can be modified with a file to fit different hand size. Avoids slide cut on web of shooting hand, increase shooting speed and accuracy Youtube installation instruction: https://www.youtube.com/watch?v=8SkSyF_hefY