Large diameter CNC-machined front sight that incorporates a light gathering fiber optic rod for high visibility and faster sight acquisition even in poor lighting. Universal design fits most shotguns. FEATURES:? The industry?s favorite bead replacement.? Available in metal or ultra-tough composite.? Fiber diameter is .078".? Fiber length is 0.5".? Universal model is metal and includes different size mounting screws.Fits:3mm thread size