This instrument fits onto a Olympus OM film camera as shown for fine close up work. I used it on a OM-1 and OM- 4t to properly focus on stars in the night sky. Great for macro as well. It might fit other cameras as well. Shown in the last pictures mounted on a Canon Rebel XT digital camera with the eyecup removed. This instrument is in perfect working order. I just do not have a need for it anymore. Included is the case shown. I travel to Victoria often and can bring it with me.