Digital Fluid-Trac™ drum level gauge is a cost competitive non-contact continuous liquid level drum gauge. It is designed for use on vertical drums (= 32" depths) storing a wide variety of media such as water, waste water, motor oil, hydraulic fluid and diesel fuel. NOT intended for use with gasoline. For use with standard 55 gallon drums. Uses ultrasonic technology to generate a high-frequency sound wave and measures the time for the echo to reflect off the target fluid's surface and return. The distance from the Digital Fluid-Trac's sensor to the liquid is calculated based on the speed of sound. The Digital Fluid-Trac™ has a LCD which continuously displays the liquid level pictorially as well as in gallon units. The liquid level is automatically updated every 15 minutes. The liquid level may also be manually refreshed anytime by pressing the on/off button until the back-light is illuminated. During this time, several readings are taken and then averaged for the displayed value. Accurate to 1 gallon with a resolution of +/- 0.5 gallon. The Digital Fluid-Trac™ drum gauge is powered by two 9 volt batteries (not included). If the battery is low, "LoB "will continuously flash to notify the user to replace the batteries. Digital Fluid-Trac™ works well on ANSI MH2 standard 55 gallon drums as it mates with closed-head standardized bunghole arrangements. The LCD mounts on top of the drum with a standard 2" NPT thread connector. A 3/4" NPT threaded adapter is included with each Digital Fluid-Trac™ so either bung opening can be used on the drums. When using the Digital Fluid-Trac™, it is important to keep the mounting perpendicular to the liquid level by storing the drums in an upright position.