The Universal Fuelhawk Aircraft Fuel Gauge can be calibrated for use in most GA aircraft. Made of heavy duty�clear plastic that has been specially formulated for use with fuels�to�resist�yellowing, fading, and cracking. Easy to Use: Simply insert the Fuelhawk�until it touches the bottom of the tank. Then place your finger firmly over the top of the opening to lock fuel in the tube. Remove and instantly see a readout in U.S. gallons of usable fuel on a calibrated scale card. For use in both main and auxiliary tanks. The Fuelhawk is ideal for when the pilot must take a less-than-full fuel load due to weight considerations or measuring how much is really in the tank. Made In USA