Reads oil level in storage tanks & sends reading to indoor receiver.Suitable with heating oil, kerosene, diesel & biodiesel B100.Fits onto any tank up to 3m deep. Easy to retrofit.Measures the oil level in the tank by ultrasonics.The transmitter needs a 20mm or 32mm hole on the tank.No power required at tank, gauge has a long life lithium battery.C/w receiver, plugs into a 230V socket displays level in ten graduations, can be up to 200m away from the tank.