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 has a black hard anodized finish. It is .375" in diameter and 1.500" in length. This model is compatible with Henry Golden Boy rimfire rifles.