Originally Posted by
Griffin2020
MMACH is correct. However, in practice I have never had it be an issue.
Both using the GPS in the car and with my cyclocomputer, I have never had any issues with vision seeing or being able to read the screen.
Oddly enough, my cell phone's screen is the only one I have that seems to be polarized perpendicularly to my sunglasses. My GPS, watch and cyclocomputer only go black if I look at them sideways.