SGT21700 Features and Benefits: - Use to test all primary electrical circuits plus any on-board computer systems . -Test computer circuits without fear of causing damage to expensive electronic components . -Completely safe to use on microprocessor control modules . -Operating range from 3-15 volts . -Current draw is less than 21 milliamps at 12 volts D.C. .Long life LED glows when voltage is sensed at probe and indicates polarity: red is positive, green is negative. Use to locate shorts, opens and intermittents. Made of high impact chemical resistant plastic. Supplied with 4 foot ground wire. All solid state construction. Circuit Master® is supplied with Protect-A-Terminal® Probe Adapter, which will not deform sensitive female terminals at computer connections. -Circuit Master® Automotive Circuit Tester .-Lifetime warranty does not cover abuse.