Dixon Bayco 2000L 2 inch NPT(M) pressure/vacuum relief cap for fuel tanksDixon Bayco 2000L 2 inch NPT(M) pressure vacuum relief cap for fuel tanks These caps are threaded into the top of fuel storage tanks Applications: they can be used as a thread in and lockable fuel filter cap they protect the tank from expansion or implosion, the internal relief valve is normally closed, but opens to relieve internal pressure or vacuum Construction: Die cast zinc body, brass screen Features Pad lockable to prevent fuel theft and