For people who use wireless keyboard and mouse. Have you ever lost the receivers? What did you do after?

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For all the wireless equipment with USB receivers I have used, I have never lost the receiver as I understand that, that tiny piece of hardware is probably more important than the actual hardware. Which can be found. But the receiver, if lost, may not be found at all.

I was just asking what would you do for that. As many people seem to lose it.
For people who use wireless keyboard and mouse. Have you ever lost the receivers? What did you do after?
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