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 Golden Boy rimfire rifles.