Lyman 17 AHB .404" high front hooded Target Sights are machined from a solid piece of steel and are designed to be mounted in 3/8"dovetail slots. They are supplied with eight interchangeable inserts (see photo and description) that are locked in place with a threaded cap.. For Many makes and models. Thanks for looking Check out my other auctions for more Firearm Related parts, accessories, and Gunsmith Services Thanks again May God Bless!!!