Viper Target Scope 1 3/8 in. .019 Green 4X Lens Machined scope made from high quality aircraft aluminum. Mil Spec 10-32 rod is extremely durable. Stainless up-pin protects the fiber. Features almost 2"of fiber optic for ideal pin brightness. Has Zeiss coated glass lens with 4X magnification. 1 3/8" diameter housing.