Tube Diameter: 30 mm (includes 1-inch / 25.4 mm adapters) Rail Mount Type: 11 mm Dovetail Recoil System: Built-in spring-loaded, shock-absorbing dampener Overall Length: 122 mm (4.8 inches) Center Height: 40 mm (1.57 inches) from rail to optical center Weight: Approximately 210 g (7.4 oz) Ring Fastening: 4 screws per ring Extra Feature: Integrated removable anti-recoil stop-pin Material: High-grade aluminum alloy with matte black finish