I have the roped verion and have found the best way is to chain hitch the rope length with a succesion of marlin spikes I suppose, and then pass my pear shape petzl krab through the last 'link' of the rope and also through the pulley, ring and retreiver clevis thingy!!. It sits very snag free but with the keyless krab design the whole lot wiggles off easily with one hand!!!! erm....ooerr!!!