Never seen them before. I'm not sure if they'd be legal, just FYI.
Usually blue light is reserved for police or other official vehicles (ambulances maybe?), and frowned upon on cars. Also, the lighted ring around the mirror could make it hard to see in the dark? If there was glare/reflection on the mirror's image?
Yes Blue is definately frowned upon. i have blue neons on the posts of my car that blink to bass. On my birthday i was headed to work lol with them just a flashin the cop did not like that at all lol . Nice 89 dollar fine . But what do you need to see? You got your rear view?