316 stainless steel thru hull for use with 3 in. marine exhaust hose features internal flapper valve to prevent backflow and no-drip lip to prevent water streaks. Stainless Steel Exhaust Thru Hull - 3 in. | Orcas 9205772 Designed for marine exhaust applications 316 stainless steel construction Stainless steel flapper helps protect against water intrusion 3 in. hose barb end Includes backing nut Drip ring prevents black streaks from forming down the side of boat Overall length 5-3/4 in. Maximum hull thickness 1-7/8 in. Outside flange diameter 4-5/8 in. Threaded area diameter 3-1/2 in.