Fernco Donuts are flexible PVC donut-shaped rings for the compression sealing of sewer pipe joints and DWV connections such as sockets, hubs, bells and spigots. They offer all of the properties necessary to create a strong, lasting joint. Fernco® Pipe Donut, Series: 44U, Fitting/Connector Type: Donut, 4 x 3 in Nominal, Cast Iron x Plastic, SCH 40/STD, PVC