The Leupold steel standard base sets are the most versatile of any mounting. The rear ring is secured by windage adjustment screws, allowing the scope's internal adjustments to be reserved for precise sight-in. Additionally, shims can be used for gross elevation adjustment, reserving the scope's elevation adjustment for bullet drop compensation dial applications. Matte Finish. Leupold Standard 2-Piece Bases give you maximum accessibility to the magazine or breech of your rifle and more flexibility in mounting scopes to bolt action rifles. These steel bases will fit both right and left-handed actions.