BKL 254 4" Long Cantilever with 1 5/8" Clamping Length is a longer version of Model 253 allowing additional overhang and scope adjustment between rings. The unique one-piece design provides flexibility for eye relief adjustment and mounting applications. Model 254 is for 1-inch scope tubes. It is designed to fit all standard 3/8" and 11mm airgun dovetail rails. Technical Specifications of BKL 254 Cantilever: - Fits 1in/25.4mm scope tubes; - Overall length: 4in; - Clamp length: 1.65in; - Ring Width: 0.6in; - Height from bottom of mount to scope tube's bottom: 0.774in; - Turret Clearance: 0.125in; - Weight: 5.1 oz. BKL Mounts features: - Strong One-Piece Clamping Base allows easy mounting of 1-inch scopes; - 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. - Oversize mounting rails? No problem. Clamping screws can be switched to BKL's unique Spreader Holes to evenly push the clamping legs apart allowing the mount base to slide onto the dovetail. - BKL mounts are manufactured from aircraft-grade aluminum alloy on state of the art machinery in Texas. BKL Technologies is the manufacturer of the largest selection of gun and airgun scope mounts in the U.S. Competition-grade scope mounting system includes scope mounts, scope rings, dovetail to weaver adaptors, and scope risers that utilize a quick-installing and self-aligning clamping system that fits both 11mm and 3/8" dovetails. BKL mounts are compatible with popular gun and airgun manufacturers. Try BKL, and discover why many shooters use no other mount.