Leupold mounts are every bit as rugged and dependable as the Leupold optics they're intended to secure. With a huge variety of mounting systems, for nearly every type of firearm under the sun, you're sure to find the perfect match for you firearm, and your style of shooting. Rear ring is secured by windage adjustment screws. STD rings are engineered to match up with STD 1-Piece and STD 2-Piece bases. Machined steel construction. Made in the USA.