DC 6-24V Copper Voltage Test PenTest smarter Test safer When under the hood, know if power is running without risking burn or shock with our DC 6 24V Copper Voltage Test Pen. Clip on + test the spark Simple (but safer) operation Use our quality build copper pen to test batteries, wires, fuses, and switches in any circumstances. Works for voltages of six to 24. Built in light indicator Know if a piece of equipment has voltage or not in an instant through simple red and green