The GATS jar fuel testers are used to collect pre-flight inspection fuel samples. Separates co-mingles fuel and water, allowing only fuel to be poured back into the tank through our special built-in filter which traps the water behind. Allowing the fuel samples to be returned to the aircraft instead of being thrown on the ground. The only "environmentally responsible" fuel tester on the market. It also filters out particulate fuel contamination, and makes octane recognition simple and certain.