Stainless steel ball chain, #13 size (bead diameter of 1/4 inch or 6.3 mm). Nickel Plated Brassl #13 B Couplings are used as connectors for this chain and are included with this product. Ball Chain is used for many applications, including: dog tag chains, beaded chains, wholesale jewelry chains, badge chains, pull chain, industrial chain, vertical blind chain, retaining chain, plumbing chain, key chains, beaded lanyards, ID chain, and many more applications. Our chain is everywhere, and our quality is second to none. Dont settle for low quality overseas imitations. Whatever the application, this chain will last.