Tactical Recoil Control Thumb Rest for Walther P99/ S&W 99 by Magloc #1320 US Patent D472,599. Reduces muzzle jump by 70% (shooting weak hand only), Does Not Fit As, Sw990, Ppq, Qa or .45 Cal 1. Improves shooting speed & accuracy. 2. Ambidextrous - fits for left or right hand shooter. 3. Prevents thumb from touching slide. Wings can be modified with a file to fit different hand size. 4. Youtube installation instruction: https://www.youtube.com/watch?v=fCQ0GD_Mpmw