YHM Front Flip Sight Gas Block (W/ Swivel and Bayo Lug). Multi-purpose front sight / gas block combination offers versitility and functionality. Machined steel body features a spring-loaded push button that locks sight in usable position. Push button to retract front sight when not in use. Split, barrel clamp design allows easy mounting to standard contour barrels without removal of flash hiders or muzzle brakes. Hex cap screws pull clamps unit tightly to barrel. Fits .750 diameter barrels. Made in the USA.