10 Foot Length Ball Chain, #15 Size, Stainless Steel, & 10 Matching 'B' Couplings This is a larger more industrial size ball chain #15 size chain has a bead diameter of 5/16 inch (8 mm) #15 Nickel Plated Brass '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.