The greatest thing since the invention of sliced bread. Use the bead stopper instead of tape or a stopper bead to prevent your beads sliding off the end of the cable before you are ready to attach a clasp or whatever. Fabulous, fabulous, fabulous. Squeeze the end-ring-handles, the spring opens up, pop the cables(s) in, and release. No more escapees! You'll want a bunch of these!
7mm By the pack of 5.