Good optical instrument for attaching FD lenses to EOS EF cameras.However:Comes with NO instructions: which way does it go? It is theortically possible to jam lenses and accessories together so they can never be separated. I do not know if this would happen with this, but a simple diagram at least wouold help!Really cheesy, cheap, generic end caps.Cheap generic box.Since the caps fall right off, a good box would help keep it together. I may have to buy good caps to protect it.All in all a good product but for $100 bucks for a metal ring with a lens they did not need to scrimp like that.