#10 stainless steel 'B' couplings are used as connectors for the #10 size stainless steel ball chain. This product is genuine Ball Chain direct from the manufacturer - Ball Chain Manufacturing in Mount Vernon, NY - which means that it is made in the USA and is the highest quality in the world. Ball Chain connectors are used to join ends of ball chain together to form loops such as those in neck chains, dog tag chains, key chains, bracelets, and custom chain assemblies. 'B' Couplings are used as connectors for larger chain sizes (*regular connectors are available up to size 8 chain, so for size 10 chain and above, select 'B' Couplings). Ball Chain Manufacturing is ISO 9001:2008 certified by the International Organisation for Standardisation and is also recognised by the Green Business Bureau as a certified "green business". Ball Chain Manufacturing is the largest manufacturer of Ball Chain in the world and the only company that manufactures its chain in the United States. Our chain is everywhere, and our quality is second to none. Don't settle for low quality overseas imitations. Whatever the application, this chain will last.