Ultrasonic Beam determines the exact level of liquid propane inside your tank * LED light indicates whether you have liquid propane at that level of the tank (green = liquid presence / red = no liquid) * Independent testing shows the GasCheck is accurate 99.9% of the time - intrinsically safe * The size of a pen it easily fits in your pocket (no installation necessary) * Wide Range of Applications including grills, patio heaters, propane firepits and all other propane related operations