STD rings are precision engineered to match up with STD 1-piece or STD 2-piece bases. Rear ring is secured by windage adjustment screws. Available in five different ring heights. Machined steel construction. Product Features Matte Black Gloss Bases for many popular rifle models available. (mounts) Forged and Machined steel construction. Versatile, and available for many different rifles. Windage Adjustable (STD Mounts) : 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 (STD Mounts) :Long Range STD mounts provide a 15-MOA slope of built-in elevation compensating for bullet drop at extreme ranges. Maximum Accessability (2 pc. Mounts) : 2-Piece bases offer maximum accessibility to the breech area of your rifle. 2 Piece Bases (Mounts) : 2-Piece bases fit right and left-hand actions, and reversible bases are available for many actions. STD Rings : STD rings are engineered to match up with STD 1-Piece and STD 2-Piece bases. Five different ring heights are available for STD bases.