I have made a film for LetusDirect.com explaining all about the different Letus adaptors. What they do, how they do it, what you need.
It looks at all three main adaptors, who they differ and what issues you will come up against.
It also talks more about 35mm DOF adaptor concepts too so a lot of the information is pretty pertinent to all 35mm adaptors really.
It’s long, so let it load up before playing if you can!