Direct from Apple Support (as of 04/15/2022): “The 4C170 version is indeed for the 3rd gen AirPods. 4C165 is for AirPods Max, AirPods Pro and AirPods (2nd generation).”
I have Apple “AirPods Pro” and read online (just about everywhere I looked) that the current firmware for the AirPods Pro & AirPods 3rd gen. (seemingly as though they run the same firmware - which, as it turns out is not the case) was “4C170.”
I checked and noticed the firmware I was running (again…for my Pros) was “4C165”; then, like an idiot, spent the better part of an hour following all the steps Apple recommends for “automatically” updating firmware on AirPods and waiting around to no avail. Seemingly, my Pros were just not updating to the new 4C170 firmware.
Ultimately, I reached out to Apple’s chat support for assistance and within 3 minutes, it was established that the “problem” I was experiencing with my firmware failing to update…was, in fact, not a problem at all; and that I was already running the latest available firmware version for the AirPods Pro - which, again (as of 04/15/2022), is 4C165.