The SC48RJ SC Series NL, XLR & RJ45 Cable Tester from Whirlwind is a cable tester designed for use with 4- and 8-pin NL cables, 3-pin XLR cables, and RJ45 data cables. Simply plug a cable into the tester and rotate the device's central switch to test the cable's conductors one at a time. LED lights will indicate how the cable is wired and whether there are shorted conductors, among other parameters. This unit runs off of (1) 9V battery.