The device in the picture: is an industrial nylon sheave intended to fit on a 'biner to create a pulley. It was sold by REI back in the mid-60's along with other rescue devices for rock climbers. I would like to try it in my suspension system (where I now use an SMC descender ring) to reduce friction in a trucker's hitch and increase the bending radius of the lines that attach at that point. Unfortunately, I can only find one of the two I originally bought and can't find an identical or similar product on the web. Has anybody seen this or a similar device for sale within the last few years? Any help would be greatly appreciated.