Fernco Donuts 2"x1-1/2" Cast Iron Hub Donut. It connects 2" service weight cast iron pipe to plain end of 1-1/2" DWV Schedule 40 plastic pipe. This corrosion resistant, flexible, Lead-Free, removable, UV resistant, underground rated donut is suitable for underground use. It provides several points of seal to accommodate possible irregularities on the pipe surface.