Got a medium to heavy weight chain or beaded necklace that needs an extra-secure clasp? Check out our rectangular 10.3mm lobster clasp in solid .925 sterling silver. Like Spring Rings, Lobster Clasps are held closed by a spring. Unlike Spring Rings, the closure is a strong pincer-like 'lobster claw' that opens with a small trigger lever, and closes shut on a jump ring or flat pierced tab. Lobster clasps are often used for medium-to-heavy chains and beading lines, for heavier necklaces, bracelets, and keychains. Their claw mechanism can be shaped as a square, oval, teardrop, or other form, depending on the desired use and aesthetics. Open jump ring provided for easier attachment to chains and loops. For even stronger joins we recommend a sterling silver split ring or a sturdy wire-wrapped connector. Jump ring size is 3.8mm, 20gauge. Clasp Length without Jump ring: 10.3mm Clasp Width: 4mm (Including lever it is 5mm) Stamped 925.