10 Foot Length Ball Chain, Number 13 Size, Stainless Steel, 10 Matching B Couplings This is a larger more industrial size ball chain #13 size chain has a bead diameter of 1/4 inch (6.3 mm) #13 Stainless Steel 'B' Couplings are used as a connector for this chain size Rustproof T304 Stainless Steel Made in USA by Ball Chain Manufacturing Since 1938. We are the manufacturer, not a reseller.