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. Made in USA. This model has a black hard anodized finish and is compatible with Henry Big Boy rifles (post 2010).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. Knurled body - affords positive non-slip cocking, use with or without telescopic sights.