This is a K&F mount adapter, well-known among vintage lens enthusiasts. It allows the use of Nikon F-mount lenses on Canon EOS M-mount cameras. Aperture cannot be adjusted on G lenses (lenses without an aperture ring) or lenses with electronic aperture control. Since there are no electronic contacts, focus, exposure, etc. must all be manually operated. The inside of the mount adapter is not treated for internal reflection. Infinity focus is supported.