The Lisle Digital Circuit Tester, No. 29050, provides an operating range of 3V to 30V DC to work on most vehicle electrical systems. With 360-degree visibility of polarity, the probe is insulated to prevent the possibility of shorting the side of the probe to other components. It has a 47" cord and heavy duty alligator clamp for secure connections. The tester is computer safe, and it will not damage sensitive electronic components. It is not for use on air bags.