"Attwood 90 P Trap Fuel Tank Vent . This baffled vent helps prevent water from entering the fuel tank, yet allows air to vent freely during normal sea conditions and washdowns. Eliminates the need for anti-siphon loop in the vent hose. Meets ABYC standards. Fits 5/8"" ID hose, max. 9/16"" hull thickness, requires 3/4"" installation hole. ...