With prices soaring, petroleum is more than ever "liquid gold." Like other valuables, fuel tanks should be kept under lock and key. Perko makes it easy to retrofit a sturdy locking mechanism in the majority of their 1-1/2" vented and non-vented fills. The black plastic 0525 Fuel System Locking Insert comes with a high-strength zinc alloy lock cylinder. When slid into the fill, spring action retracts the cams, which then lock onto the hose bib once the device is fully inserted. A handy dual purpose key opens the protective metal fill cap and operates the lock.