Amazon.com: Mic-Lock Microphone Blocker – Audio Input Blocking Device (3.5mm) for Laptops, Smartphones, Tablets, and Desktop Computers - Data Security, Privacy Protection (Single, Metallic) : Everything Else
Microphone Blockers can be custom printed with your brand details.
Microphone blocker - Wikipedia
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Amazon.com: Mic-Lock with SOUNDPASS Lightning Microphone Blocker – Audio Security for iPhones and iPads Audio Security, Privacy, Counter-Surveillance - Hear Music No Eavesdropping : Electronics
Microphone Blocker für Laptop, Handy & iMac von Privise.io