Multi-purpose front sight works as a fully functional gas block, plus delivers lifesaving backup when primary optics fail or become hindered by low light or poor weather conditions. Machined, steel body features a spring-loaded pushbutton that locks sight in the deployed position. When not in use, simply depress the button and fold down for an unobstructed view through your optics. Protective ears guard the sight post from blows incurred during duty. Split, barrel clamp design allows easy mounting to standard contour barrels without removal of flash hiders or muzzle brakes. Hex cap screws pull clamping halves tight to barrel for complete sight immobilization when properly tightened. Durab Mfg: Yankee Hill Machine Co., Inc. SPECS: Steel, phosphate-coated finish, dark gray. 1-7/8" (4.8cm) long, 1-3/16" (3cm) wide. Sight Post - 2A 1/4" (5.7cm) high when raised. Fits standard, .750" diameter barrels. YHM-9394 - 6 oz. (170g) weight. YHM-9835A - 7.7 oz. (219 g)