Canon "Flash Unit Coupler" for some late model Canon rangefinder cameras and early SLR cameras. If you've ever wondered what that large round bayonet socket is on the side of the camera is for now you know. Used, a few marks, works. Beware, we've seen some of these advertised for sale that appear to be missing the center portion! Ours are complete. 

WHO WE ARE: Oddog2 is a husband/wife team, home-based small business specializing in the buying/refurbishment/selling of primarily photographic equipment. We do occasionally have other types of things to sell that come to us as a result of our search for camera-related items. We have over 50 years of experience with photographic equipment, both as a shooter (17 years newspaper photojournalist) and as a collector/restorer/seller. We have been on eBay as Oddog or Oddog2 since September 1999.