The Triplett Line-Bug 4 (9615) is a simple tester to determine if there is damaging telephone line current on RJ-11 and RJ-45 lines. Some LAN lines have telephone current on previously unused pairs. Pre-testing LAN lines with the Line-Bug 4 before testing with a LAN Tester may prevent damage to it. Checks RJ45 connections wired for 568A/B or USOC pinouts. Tests 1-, 2-, 3- and 4-line jacks. Four tricolor LEDs indicate Current, Polarity and Ringing/AC Volts. Self-powered by line voltage. If any LED lights in USOC or 568A/B switch positions, voltage is present. Founded in 1904, U.S.-based Triplett Test Equipment continues to be on the leading edge of specialized testers. Whether supplying vital test equipment to the U.S. Signal Corps during WWII, or providing the railroad industry with essential testers to ensure the safety of their crews and the public, Triplett prides itself on developing innovative, reliable, and durable test equipment that also won't break the bank. Triplett's catalog contains a wide array of test equipment parts and accessories such as multimeters, voltmeters, cable testers, security cameras and security camera accessories, wire cable mapping kits, video monitors, and other specialty testers. They serve industries such as HVAC, security, electronics and electrical, telecom, and more.