Roll Over valves work by allowing air into the tank to replace the fuel being used, air out of the tank due to heat expansion and a positive shut off to prevent fuel escape due to the vehicle rolling over. These are made from billet aluminium and anodised to protect it. It hasa ball bearing inside the bottom half that allows the air to breathe easily without any restriction. However, if the tank is turned upside downthe ball bearing drops to the top of the fitting effectivelycutting off the exit. This is designed to work with the female ORB facing down and theMale AN fitting Facing up. Available in both -6AN and -8AN in blue, black and silverfinishes.