Sea-Dog hose thru-vent is designed for cabin or bilge ventilation. Constructed of injection-molded ABS, it is UV-resistant. Thru-vent is for use with 3" / 3-1/8" exhaust hose. Installs with four #8 FH fasteners (not included). Note: Avoid contact with acetone or strong solvents. 3-11/16"L x 3-11/16"W x 2-7/16"D.