The Williams WGRS Peep Sight is an Aperture Sight that fits popular rifles. 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). We have Williams WGRS Peep Sights for several popular rifles.