Soux Chief 867-P3 Pac Solvent Weld Roof Drain for Drainage Systems Polypropylene (polypro) or Cast iron dome strainer Abs or PVC solvent weld connection Uses key and keyhole alignment system on dome strainer and gravel guard Polypro dome strainer and PVC gravel guard are U.V. Resistant Brass thread inserts accept collar and clamp screws