The WGRS is an Aperture Sight that fits Thompson Center Arms Encore, Pro Hunter, Omega, and Impact. An aperture sight (aka peep sight), mounted as close to your eye as possible, removes a huge amount of aiming error by simply increasing the sight radius (the distance between front and rear sights). Also, aiming error from rear sight light reflection is virtually eliminated with an aperture sight... so that the angle of the sun will not change your point of impact. Finally, the aperture itself improves the focus of your sight picture by funneling the light through a hole. (A camera will do much the same thing when you reduce the size of its aperture... the depth of field improves). This sight mounts in the scope mounting holes at the REAR of your barrel and uses the factory front sight. You might also be interested in our PeepRib Sight System. See all of the TC Muzzle Loader Accessories at our TC Muzzle Loader Home Page.
(Note: Threads on the aperture are standard 7/32 x 40)