This is a DUAL purpose bead, primarily designed to act as an elastic puller bead, but with the added advantage that it comes with 3 different size bores to suit various sizes of elastic. With the smallest bore at 0.5mm this will not only prevent the smallest of elastics pulling through the bead, but this is where the beads added feature comes in. By matching the bead to your elastic, the bead can be used to tension your elastic at the puller end of your kit, making your elastics more versatile.