Fernco Donuts 4"x3" Cast Iron Hub Donut. It connects 4" service weight soil cast iron pipe to plain end of 3" PVC Schedule 40 plastic pipe. It is corrosion resistant, flexible, Lead-Free, removable, UV resistant, underground rated, and underground use. It has a maximum working pressure of 4.17 psi and a maximum working temperature of 120°F. It comes with a 1 year warranty.