The transmitter sits on top of the tank and using ultrasonic level measurement techniques, constantly measures the level of oil in the tank.
It then transmits that information to the receiver which is plugged into an electric wall socket, located in a convenient place within the house.
The height of the liquid is displayed on a LCD screen on the receiver. The householder can monitor the level of oil in their tank from inside their home.
When the level of oil in the tank gets below 10%, the fuel dispensing pump symbol appears, indicating to the householder that it is time to order some more oil.