This vent fitting mounts in a 3/4" hole in the fill plate of your fuel cell. 8AN 90 degree male fitting allows easy, low-profile hookup of a -8 AN or 1/2" ID rubber vent line. Includes mounting nut and sealing washer. The valve is not spring-loaded. It depends on gravity to close the valve and stops the flow of fuel in the event of a rollover.