Carlson's ambidextrous Black Hammer Expanders for a post 2010 Henry Big Boy Rifle provide easy cocking for left or right hand shooters at all times. Installation is easy with a set screw. A knurled body allows positive non-slip cocking. They are balanced and lightweight which helps prevent uneven wear of the trigger and sear surfaces. Ambidextrous ? Provides Easy Cocking for Left or Right Hand at All Times Easy Installation Balanced and Lightweight ? Helps Prevent Uneven Wear of Trigger and Sear Surfaces One size Fits All T.C. Contenders and Most Exposed Hammer Firearms