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. Two spacers included to allow hull thickness up to 1".