Hammers One Piece Scope Mount AM4L with Stop Pin for Magnum Airguns Solid one piece design and built-in threaded stop pin for max. holding power Good for 1inch tube full size rifle scopes with objective OD(outside diameter) 40mm or less Fits onto 3/8inch dovetail bases or grooved receiver top 4 clamping screws at the bottom for max. holding power Authentic airgun specialty Hammers products