Williams Gun Sight Twilight Eye Cup 1/2" Diameter x .125" Aperture

Williams Gun Sight Twilight series receiver eye cup. Twilight apertures are designed for shooting under poor light conditions, early morning, late evening, deep timber and other inclement conditions. They create a sharp contrast that gives quick definition to the aperture hole, and they eliminate "fuzz" with which many shooters have trouble. Will fit most Redfield, Lyman etc. sights with 7/32x40 thread.