This Williams Gun Sight Company manufactured WGOS red fiber optic adjustable rear sight assembly with both mounting screws is for a wide variety of Thompson Center in-line muzzle loading rifles including the Black Diamond, Encore 209x50, Fire Hawk, Impact, Omega, System 1, Thunder Hawk and Triumph when used with the taller .445" high fiber optic front sight and is in excellent condition with light wear. (file photo)

Warning: You might want to purchase the Williams .445" high fiber optic front sight if your current front sight is shorter or taller so as to have proper alignment when sighting in your muzzle loader.