Ball Chain #10 'B' Couplings Aluminum 100 Count #10 Aluminum 'B' Couplings are used as a connector for this chain size (sold separately) 'B' Couplings can also be used to form adjustable loops with the chain 'B' couplings are also available in other materials to match each specific chain type Bulk Packed Made in USA by Ball Chain Manufacturing Since 1938. We are the manufacturer, not a reseller.