1. Tightly clamped port, standard interface: Suitable for network cable interface, RJ11 interface of twocore telephone line can be transferred through the crocodile clip line. 2. Network cable calibration function, test continuity: Insert the connectors at both ends of the network cable to be tested into the transmitter and receiver interfaces respectively. Set the transmitter function to 'line' and use the line light to determine line short circuit. 3. Positive and negative pole detection, DC level test: Set the function selection to 'Line Hunting' and press and hold the 'Switch' button for more than 2 seconds. The 'Line Light' will flash. Both ends of the clips are inserted into the RJ11 socket and power supply respectively. 4. Comes with a headphone cable for clear listening: Equipped with a headphone cable for operation in noisy environments. The volume can be adjusted with the knob. 5. Flashlight lighting to illuminate the front: Flip the 'receiver' light switch upward in dark or lowlight environments to illuminate and facilitate work.