The OEM Automotive Tools Digital Display Circuit Tester, No. 24451, detects voltage, power, ground and circuit condition and provides a display of the precise voltage. The tester can read the voltage measurements, from 5V to 30V DC, of 6V, 12V and 24V systems. The LED indicates blue for ground and red for power. The tester, which offers with a 3m coil cable and includes strain relief, is computer safe, but should not be used on airbags.