The Retro-Adapter-Professional is for use with Canon EOS Cameras (e.g. EOS 300D/400D/40D/Digital Rebel/350D/Digital Rebel XT/20D/10D/D60/D30 and other). It's handling is better than the Standard-Edition because of the 58mm-screw-thread and you can use it with light lenses (e.g. Canon 18-55mm/3,5 - 5,6) and those which are more heavy (e.g. Canon 28-105mm/3,5 - 4,5). For future use you can adapt it with separate filter-adapter-rings (not included) to other lenses. You can magnify with the adapter up to a factor of 5:1 (normal macrolenses go only to 1:1).