McKay All-Purpose 6-12V- AC Circuit Tester: Professional Electrical Diagnostic Tool for Electricians- Light Indicator Glows when House & Car Fuses, Low Voltages Light Sockets & Circuits are Complete MULTI-PURPOSE, VERSATILE ADAPTABLE FUNCTIONS: Great Electrical automotive tool for house & car fuses, low voltage light sockets & circuits. By connecting the flying lead to an earth (ground) reference and touching the screwdriver tip to various points in the circuit, the presence or absence of voltage at each point can be determined. For use on cars, trucks, SUVs, ATVs, boats, trailers, vans, RV's, motorcycles, airplanes and snowmobiles. LIGHT INDICATOR WHEN LIVE ELECTRIC WIRE IS DETECTED: Our lamp were designed to glow when measured 6-12v electricity connection is complete. Excellent instrument to locate shorts of wires or to test the drains in cars. If the light fails to light up, you know that the wire isnt live. No battery required, the electricity is pulled from the two wires that connect by the tester. SAFE, INSULATED ALLIGATOR WIRE: Connected with heavy duty insulated alligator clip and 4-1/2 ground wire. Our circuit test was manufactured with high quality wiring material for your safety. Accidental contact with live wiring can result in an electric shock. For your safety, rubber gloves usage will protect you from getting effected from electric shocks. NEEDLE SHARP STEEL PROBES: easily piercing wire insulation to check circuit. Helps find broken and live wires efficiently. When testing circuit breakers or fuses, just pierce through the hot wire on one side of the clip side of the tester and point the screwdriver edge at any other neutral wire to test the electrical power. Both wires on each side need to be live for the tester to glow. SPECIFICALLY ENGINEERED FOR LOW VOLTAGE ELECTRICITY: Maximum checking voltage for electrical circuits and accessories is 6-12V. Electric charge inalternating current(AC), changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction. Tester may bust if utilized for higher voltages electricity. Be careful prior to testing if youre applying the right voltage tester to the electrical equipment.