Fernco 3"x3" Flexible Coupling with 2 Stainless Steel Clamps. It connects cast iron or plastic to cast iron or plastic. It is corrosion resistant, flexible, Lead-Free, removable, UV resistant, underground rated, and underground use. It has a maximum working pressure of 4.3 psi, a maximum working temperature of 120°F, and a 1-year warranty. 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. All flexible couplings are clearly marked with part number, size, and pipe material that the coupling will connect to.