The Outlet Reducer Ring fits on 18 in. catch basin drains to reduce the size of the basin opening to accommodate connection to 3 in., 4 in., 6 in., and 8 in. drain pipes and 6 in. outlet plug. Use with outlet adapter (1242, 1243, or 1245) to connect to 3 in. & 4 in. drain pipes; use with outlet adapter (1266) to connect to 6 in. drain pipe; use with outlet adapter (1888 or 1889) to connect to 8 in. drain pipe. Made of high-impact polystyrene (HIPS) treated with UV inhibitors.