Sea Dog Scupper valve. 2-13/16" OD X 1-7/8" ID.This Scupper Valve provides a water exit for boats with self-bailing cockpits. Ideal for above the water line drainage. Valve features soft black flapper that seals to prevent backwash. Compatible with most self-bailing applications. Constructed of durable injection molded nylon. Surface mounts with four #6 FH fasteners (not included).