ViewSonic Sensor is a battery operated liquid ultrasonic level sensor that is capable of providing the user with instant level indication at a glance. The ViewSonic Transmitter uses ultrasonic (sound wave) technology to measure the distance from the sensor face to the surface of the liquid in chemical tank or sump, then back to sensor face this is referred to as (time of flight). As the liquid product inside the tank decreases the distance that the senor measures increases accordingly. The current level measurement can be viewed directly on the LCD screen located on the sensor or via the remote display. No wiring is required as the level data is wirelessly transmitted to the remote display. After completion of programming the display calculates and displays the amount of liquid remaining in your tank in gallons, inches or as a percentage of the tank capacity. In addition, The ViewSonic sensor can be mounted directly on the top of the tank.