Carlson's Hammer Expander provides easy cocking for left- or right-hand use at all times. Balanced and lightweight it is easy to install and helps prevent uneven wear of trigger and sear surfaces. The knurled body affords positive non-slip cocking and it may be used with or without telescopic sights. The hammer expander is .375" in diameter and 1.5" in length. A. This model has a black hard anodized finish and is compatible with Henry Big Boy rifles.Features: AMBIDEXTROUS - provides easy cocking for left or right hand at all times HENRY HAMMER EXPANDERS EASY INSTALLATION BALANCED & LIGHTWEIGHT - helps prevent uneven wear of trigger and sear surfaces KNURLED BODY - affords positive non-slip cocking Use with or without telescopic sights HARD ANODIZED FINISH - available in black