The phrase "mirror housings" refers to the protective casing or coverings that hold and support mirrors, typically found on vehicles such as cars and motorcycles. Full definition
For instance, when another vehicle is hidden in the area — such as in a driver's blind spot — a yellow LED on the exterior mirror housing lights up. (autoweek.com)
A small camera in the passenger - side mirror housing helps drivers get a better view of what's hiding in their blind spot. (autoguide.com)
On the previous generation, I believe they were integrated into the rearview mirror housing. (corvetteblogger.com)