Suitable for testing DC circuits with a voltage between 3 and 30 Volts. No ground or clip necessary – simply touch some thing that acts as a ground (bare metal part on a car) and use the probe to test for power.. Bi-directional polarity testing: Power and Ground. Dual colour LED indicates: Red for power, green for ground on 6V, 12V and 24V systems. Compact size for ease of use in confined areas. Computer safe.