Fangrui Product Details Multi-functional: There Are Open Circuit Of Short Circuit Testing Function, Telephone Wire Finding Function, Tracing Cable Function, Dc Level Testing Function (dc 3~10v), Network Line Finding Function, Network Cable Proofreading Function, Etc. Low Voltage Prompt Function: When The Function Selection Switch Of The Transmitter Is Turned To Finding Position, If The Battery Voltage Is Lower Than 6v, The Transmitter Scan Led And Line Sequence Led Flash At The Same Time To Remind The User That The Battery Needs To Be Replaced. Earphone Function: In Noisy Environment, Earphone Can Be Used To Prevent Interference From The Outside. Spotlight Function: You Can Easily Work As Usual While Putting On The Light Switch At Night And In The Dark. Volume Adjustable Function: Turn The Volume Adjustment Knob On The Receiver (the Higher The Volume, The Higher The Sensitivity) Until The Sound Is Appropriate. Energy Saving: Automatic Delayed Shutdown. About 1 Hour After Start-up, The Device Automatically Enter The Shutdown Sta