[e28bmw]

Does anyone know whether the anti dazzle function is just the photo-chromatic glass or whether there is any electronics behind it? The reason I ask is that I have some second hand mirrors that were purchased independently and one is anti dazzle but the other isn't. I'd like them both to be anti dazzle if it's as simple as changing the glass.
The car is a pre LCI e92 if it makes any difference.

Thanks