Buyers Products Self-Grounding Back Up Alarm delivers a low frequency tone to warn pedestrians and other drivers. It meets requirements of OSHA, the U.S. Bureau of Mines, GSA, all state regulations, and SAE J994 criteria. The alarm has a voltage range from 12V to 24V DC and can function in temperatures between -22?? and 122?? Fahrenheit. It's epoxy-sealed to resist moisture, dust, and vibration.