If you use propane gas for appliances in your camper, RV, boat, or even at home in your backyard grill, this handy Dometic LP Gas Checker will make life easier for you. No more wondering how full your tank is – this practical device tells you in just a few seconds! The fill-level indicator is based on ultrasonic technology and can be used for all commonly available steel and aluminum propane tanks with a diameter of 8 to 14 inches (200 to 350 mm). Simply press the rubber-tipped probe horizontally to various points on the tank wall and watch the indicator light change. A green light means there is gas at the point where the measurement is taken; a red light means there is none.