The SC48RJ Tester provides rapid, positive testing for NL4 and NL8 SpeakON type multiline speaker cables, RJ45 type data cables, EtherCON cables and XLR cables. Rotating the central switch applies voltage to the cable conductors one at a time. A SEND LED indicates the pin to which the voltage is being applied, and a RECEIVE LED indicates where it returns, clearly revealing, shorts, opens and cross-wires.