Zinc coupling nuts

A Zinc Coupling Nut is a light-duty fastener with a zinc-plated finish suited for dry, indoor fastening applications where heavy corrosion resistance is not required.

These are sometimes called “coupler nuts” or “extension nuts”. Coupling nuts have a cylindrical body, a fully threaded interior, and open ends on each side, designed to join two externally threaded fasteners end to end. Their elongated hex bodies allow easy tightening with standard wrenches and sockets, and the zinc plating provides basic corrosion protection for general-purpose interior assemblies.