Roof Drain - Zurn PVC Heavy DutyThe Zurn 12" diameter main area roof drain has a PVC body, complete with steel threaded inserts for increased strength and longevity. Standard to the roof drain is a cast iron clamp device with an integral gravel guard and a polyethylene dome strainer. Features: Heavy walled PVC body, complete with galvanized steel threaded inserts to accept securing bolts Dura Coated cast iron clamp device with integral gravel guard Heavy duty, high impact