This Williams Gun Sight Company manufactured WGRS series receiver peep sight with Twilight aperture and both mounting screws is for the Winchester model 1300 and 1400 Slug Hunter shotguns with factory drilled and tapped receivers and is in as new condition. The receiver peep sight mounts on the top rear section of the receiver where your scope mounting base would normally attach.  (file photo)

Note: This is a CFnParts exclusive non-catalogued Williams Gun Sight Company manufactured receiver sight