This device is the Fluke Networks Pro3000F Filtered Probe. It is a professional tool used with a tone generator to trace cables and identify wire pairs accurately, even through walls or wood. ODP Business Solutions Key Features of the Filtered Probe: Innovative Filtering Technology: Features the ability to block interference and hum from external electrical sources (like power and lighting cables) at 50 or 60 Hz. Filtering Mode: You can switch between filtered mode (LED indicator lights green) and unfiltered mode (lights red) with a single button press. Powerful Speaker: Allows clear hearing of the tone in noisy environments or when tracing cables behind drywall. Auto-Off: The probe automatically turns off after 5 minutes to conserve battery life (9V). Headphone Jack: A 3.5mm jack is available for using headphones in extremely noisy environments. Global Test Supply How to Use for Wire Tracing: Connect the Tone Generator: Connect the tone generator (the small square device in the picture) to the cable to be traced using alligator clips or an RJ-11 connector. Power On the Probe: Press and hold the power button on the probe for about one second. Trace: Move the probe tip close to the cable bundle; the volume will increase as you get closer to the correct cable. Confirm (SmartTone): When using a compatible tone generator, you can short the circuit at the far end of the pair, and the tone will change to confirm you have found the exact pair you are looking for. Link to a video of how it works Note that the device is valued at over 650 SAR And selling to the highest bidder due to no longer needing it Please do not lowball