Barrel: Used on most rope chains to make the chain more secure. The barrel clasp looks like part of the chain and makes it easier to get a pendant on and off. Lobster claw: An interlocking catch with a spring mechanism and a safety lock. Spring ring: Used on lightweight chains. Toggle: Consists of a ring on one end of a necklace or bracelet and a short bar on the other end. The bar slides through the ring to keep it closed.