This adaptor is supposed to allow you to use an old FD Canon lens on a Canon EOS digital camera. When I opened the package there were no instructions, so I had to use my reasoning powers to figure out how to attach it to my Rebel body. I finally got that far and then attached an old Canon FD lens, a 35 to 135, expecting great things. Well it did fit, but the Rebel's electronics doesn't couple with the lens, so there is no illuminated image as you look through the viewfinder. I took some shots and they were all dark and unusable. So, I sent it back and got a refund.
Bottom line: This product didn't work as I thought it should, and I do not recommend it to any Canon owner.