The FuelHawk fuel gauge is made specifically for the Cessna 182 aircraft with standard tanks with a 39 gallon usable fuel capacity. It is an essential tool when pilots need to take on less-then-full fuel due to weight considerations or when the exact amount of fuel left in the tank.It is constructed of a heavy-duty clear plastic and simple to use — just insert the FuelHawk until it hit the bottom of the tank, place a finger over the top, remove from the tank and read the readout in U.S. gallons of usable fuel on the calibration card.