attwood Replacement Cover 911526-1 for P-Trap Fuel Tank Vent Black-Boat Replacement cover for standard mount p-trap fuel Tank Vent. These vents help prevent water from entering the fuel tank, yet allow air to vent freely, during Normal Sea conditions and wash-downs. P-trap vents eliminate the need for an anti-siphon loop in the vent hose. Splash-resistant, corrosion resistant Vents air from your boat's fuel Tank as you fill the fuel tank.