L.H. Dottie RRC21 Reducing Rod Coupling, 3/8-Inch to 1/4-Inch Diameter by 1-Inch Length, Zinc Plated, 50-Pack Reducing rod couplings Zinc plated steel Rod couplings are used to couple threaded rod for extended lengths Reducing rod couplings are used when working with two different thread diameters 3/8-inch to 1/4-inch diameter x 1-inch length