Medium 3.2mm brass ball chain clasps, for use with 3.2mm bulk ball chain. White-plated components are generally grayer, but also more durable, than silver-plated components. (White plating is also known as "imitation rhodium" and "silvertone".) These clasps hook both ends of the chain together, to make a necklace or a key ring. If the clasp appears too tight to fit on your chain, gently loosen the clasp with an awl or chain-nose pliers.