Astro Pneumatic 7760 Circuit Tester Cordless The Astro Pneumatic 7760 Circuit Tester Cordless has a special designed V-Tip needle that allows safe piercing and prevents side-slipping when piercing wires insulation. V-Tip can be removed to test hard to reach places. Designed to be used on DC powered circuits with voltages between 3 and 28 volts. This unit does not require ground wire or clip and is safe with ECMs, Sensors, Transducers, Airbags, etc. and works with replaceable long-life alkaline batteries.