Pixman, interesting that someone would know what it was, I'd never heard of one till Charlie got into film school. No bearings, with the loads involved and polished shafts (not drill bits) brass bushings should last a long time. It will give a four to one increase, followed by about a 1 to 4 decrease to the lens, or overall 1 to 1. Will see how it feels, can either shim the gears or use a belleville washer to preload the gears. He has a Canon 5D at the moment, but hope to build the mount fairly universal.