Fits Williams WGRS ONLY. Longer shanks allow correction for proper eye relief. Standard or brass-ringed, Twilight (TW) aperture. Mfg: Brownells 7/32"-40 thread. 3/8" Twilight, Long Shank (TW L/S)Aperture Packs include three, 3/8" O.D., long shank apertures: one each with .050", .093" and .125" holes.
