Sea-Dog Thru-Hull w/Scupper Valve - Injection Molded Acetel [520510-1]Thru Hull with Scupper Valve Injection Molded Acetel This Thru Hull Scupper Valve mounts through the transom and provides a water exit for boats with self bailing cockpits. Ideal for above the water line drainage. Valve features a soft black flapper that seals to prevent backwash. For use with 1 1 2" hose. Compatible with most self bailing applications. Constructed of injection molded acetal. Installs with four #6 FH fasteners (included).