Keeping you Ready for the Road Ahead , the Fuel Tank Accessories Non-Locking 1/4-Turn Fuel Cap prevents your diesel fuel from being contaminated by outside environment factors, such as dirt and dust. To make certain this gas cap replacement is the right fit for your truck, always measure the inside diameter of the fuel cap. Rest with confidence that both your fuel tank and fuel system remain protected with this fuel cap. FleetPride is your First Click in Heavy Duty .