Features and Benefits: * Operated between 3 to 28-Volt * No wire or clip needed while diagnosing polarity * Made of rugged chrome metal * Contains LED and buzzer indicator * Includes long-life alkaline 23A batteries * Safe for 6 and 12-Volt systems This unit does not require ground wire or clip and is safe with ECMs sensors, transducers, airbags, computers, etc.. Its special designed V-tip needle allows safe piercing and prevents side-slipping when piercing wires insulation. V-tip can be removed to test hard to reach places.