I was looking at all the black boxes on my front windshield and noticed the slotted black box on the driver left side of the mirror had no information in the manual that I could find. Anyway, it had come lose and I used some 2-way sticky dash cam tape to fix it. The fact that it is slotted and none of the others are not would mean something?????
A temperature sensor or microphone could be under it, or it is simply venting for cooling electronics.
