NOYAFA NF-813CMain function1. Quickly finding the required line pairs among numerous ones.2. Trace cable with continuous and clear tone, AC Current rejection.3. It tests physical connection status of network cable, such as open , short , miswire and split connection4. Hub blink for locating network port by the flashing port light on Hub / Switch. 5. Telephone Line Test: judging TIP or PING line and judging whether the telephone line is idle, ringing or off-hook.Benefits:LED indicates connections and faults . Flashing assists use in dark corneres of the receiver . Rotary switch choose the function easily . Test crosstalk when wiremapping