The Panagor Auto Tele Converter 2x is a classic teleconverter that fits between the camera body and lens. It doubles the focal length of the attached lens, bringing distant subjects closer in the frame. For example, a 50mm lens becomes a 100mm lens.
As with most 2x teleconverters, it reduces the available light by two stops and may affect image sharpness. The SR designation generally refers to the Minolta SR mount, but please check the mount of this particular item before purchase.