Phot r rear lens cap compatible with canon is a plastic lens cap fitted for the rear of canon lenses the rear lens cap is placed on the rear mount of your lens when the lens is not in use on your camera it protects that all important parts of your lens from scratches dust water and fingerprints fitted for the rear of canon lenses placed on the rear mount of your lens when the lens is not in use on your camera it protects that all important parts of your lens from scratches dust water a