Fernco Couplings have earned a reputation for consistent, superior performance, giving you full confidence in their quality and reliability. The dimensional flexibility of Fernco couplings ensures leak-proof pipe seals on virtually any pipe material: plastic, cast iron, asbestos cement, clay, concrete, steel, copper and ductile iron. Fernco® Stock Coupling, Standard Flexible, Series: 1060, Fitting/Connector Type: Coupling, 4 in Nominal, Plastic Socket, 3.97 in Length, 4.3 psi Tested, Flexible PVC, -30 to 140 deg F, 5.01 in ID