Product Details:

• For Use on Any 6 to 12 Volt DC System
• 
  
  This CRL Low Voltage Circuit Tester is designed for use on all six to 12 volt DC systems. To use, simply ground the clip on any metallic surface on the car, push the point through the insulation of the cable being tested until it makes contact with the copper conductor inside. The bulb in the handle will then light if the wire is "hot".