TheNIBCO 4 in. x 3 in. PVC DWV closet flange features a spigot connection. The closet flange is secured to the floor of the dwelling so that a toilet can be affixed to it and allow for a pipe connection (under the floor) to continue the piping for evacuation of the used water. Polyvinyl chloride (PVC) is the most frequently specified of all thermoplastic materials because of its light weight, durability, and cost-effectiveness.