The Apollo Ultrasonic is a two-part level measuring device, consisting of a transmitter (measuring device) and a receiver (display). The level measuring device measures the distance to the current fill level in the tank using ultrasound and transmits the data via radio transmission to the display device. The receiver is plugged into a well-visible free socket (230 V/AC). The display device continuously shows the current tank content in a 10-level bar graph and blinks when the alarm level is reached. The device is used for monitoring tanks containing heating oil, diesel, and other liquid media such as lubricating oils, biodiesel, used oil, cleaning agents, Ad Blue, and water.