Electronic – this cable/device

cablesledplug

I hope I'm on the appropriate site.

Does anyone know what this thing is?

It has a mini mono plug.
The white square is slippery..but it is not covering double-sided tape.
A white LED did not light up when I plugged it into a mic input on my PC.
I thought there were little holes and it might be a mic but they are small indentations, not holes.

Thanks!

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Best Answer

That's an infrared transmitter for extenders or control systems. That plastic chunk with the IR LED gets glued on a device like TV or Blu-Ray player so that it shines on the device's IR receiver.