The Leupold steel standard bases and rings are the most versatile of any mounting system we offer. 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. Features: Forged and machined steel construction Versatile for many different rifles The forward part of the base accepts a dovetail ring, locking it solidly into position, the rear ring is secured by windage adjustment screws Long range STD mounts provide a 15 MOA slope of built in elevation compensating for bullet drop at extreme ranges 2-piece bases offer maximum accessibility to the breech area of your rifle 2-piece bases fit right and left hand actions STD rings are engineered to match up with STD 1-piece and STD 2-piece bases