Coupling nuts are threaded fasteners used to join two male threads, most commonly threaded rod. The outside of a coupling nut is typically a hex so it can be driven with a wrench. Coupling nuts are also used to make up long rod assemblies from shorter lengths of rods. Coupling nuts are also available in reducer versions, which can be used to connect two different sizes of threaded rod or fasteners. Available in coarse and fine thread.
Coupling nut dimensions are described by the industrial fastener institute in standard IFI-128. Albany County Fasteners offers coupling nuts in stainless steel, hot dipped galvanized steel, and zinc plated steel finishes.