Ensuring you are Ready for the Road Ahead , the Fuel Tank Accessories Locking Fuel Cap protects your truck's diesel fuel tank with the anti-theft fuel tank cap that features a safety crossbar and chain. To ensure this fuel cap is the right fit for your Volvo, Mack or International truck, always measure the inside diameter of the fuel cap. Rest assured your diesel fuel remains safe with this heavy duty fuel cap. FleetPride is your First Click in Heavy Duty .