For adapting Canon FD lenses to GuerillaBeam projectors (with the ability to focus to infinity). Unlike the other GuerillaBeam lens adapters lens adapters, this one is not very robust. (that's why it's separate).If you'd like to connect an FD lens to GuerillaBeam, I'd rather recommend an adapter to an intermediary lens mount. Focus to infinity can still be achieved this way, by attaching to the shorter light side of GuerillaBeam and using an extension tube.