MT74/1 or 7100221884 Item 7 in the image.
Replacement boom Mic assembly for CH3 FLX2 headsets
Note that if your Mic is muffled or insensitive it can be cleaned with Telecoms handset cleaner or IPA solvent.
If mic contamination is an ongoing problem this Mic Protection tape may help.
PEL-MIC-MT74/1
Click here to view answers to your questions about radio and wireless voice communications.