About this item BKL 300DOVETAIL SCOPE SINGLE RING – Designed for the shooter who needs stability and prefers independent rings; Model 300 is for 30mm diameter scope tubes and fits all standard 3/8″ gun and 11mm airgun dovetails ONE-PIECE CLAMPING BASE – Strong one-piece clamping base of BKL-300 scope ring allows quick and easy mounting of 30mm scopes, and also guarantees that when it’s mounted on a scope rail, your scope is going to be in perfect alignment with the bore AUTO-CENTERING TECHNOLOGY – Patented Auto-Centering technology solves the problems created by varying mounting rail widths; Clamping Legs move equally as the clamping screws are tightened keeping the scope centered on the rail ROBUST AND DURABLE – BKL 300Single Dovetail Ringmount is manufactured from aircraft-grade aluminum alloy on state of the art machinery in Texas and finished in tough Matte Black paint for years of good looks and dependable service TECHNICAL SPECIFICATIONS Of BKL-S-300 Single Ring – Overall Length: 0.60″; Clamp Length: 0.60″; Ring Width: 0.60″; Bottom of mount to bottom of scope tube: 0.979″; Weight: 2.2 oz; This item sold as a single mount only