When equipment begins to fail due to an air or gas leak or vibration, or electrical discharge, the leakage point emits an ultrasonic sound wave that is above the natural range of human hearing. The ULD-405 Ultrasonic Leak Detector converts this ultrasonic sound into a signal that can be used to pinpoint the exact location of the equipment failure. Find air leaks that drop down performance and incur additional power consumption, requiring more energy to compensate lost pressure. See the strength of the leak clearly on the large LCD bargraph and identify the source of the leak by listening to the converted audible sound emitted via the earbuds.