GXR MOUNT A12 is compatible with the M mount, which boasts a long, distinguished history and an extensive range of lenses. Besides being able to mount Leica M lenses, lenses with many more types of mounts can also be accommodated if a mount conversion adapter is used. Rediscover the appeal of many "gems" of the lens field as well as other "old friends" from your own lens collection. Focusing is done manually. A checking device is included for use in confirming whether or not your lenses can be physically mounted.