Network cable proofreading: Insert the RJ45 network cable into the transmitter and receiver interface, and the transmitter press the "Align" button. Line sequence light determines a short circuit in the circuit Crystal Port: Suitable for RJ45 network cable interface, RJ11 interface, dual core telephone line can be connected through crocodile clip Measure DC level function: Press and hold "Find Line" and "Switch" for more than 2 seconds, then insert the crocodile clip into RJ11. Clamp both ends of the power supply and press the button until the "line sequence light" flashes Support earphone: Equipped with an earphone, adjustable volume for noisy environments Flashlight function: In a dark environment, turning on the flashlight makes it easier to work Specifications: Battery used: 6F22 9V battery (not included) Flashlight: built-in flashlight Weight: transmitter 62g/receiver 77g Telephone line search function: support Power cable line search: support Low voltage prompt: support Open circuit and short circuit test function: support Interface: RJ11/RJ45 Material: ABS plastic process Network line search function: support Network cable calibration function: support DC level test function: support Single and double audio switching: support Lighting/shielded wire: support Automatic shutdown: about 1 hour after power on, the line finder will automatically enter the shutdown state Headphone function: in a noisy environment, you can plug in headphones to operate without external interference