[commodorenutt]

To change the zone it's only a matter of holding down certain buttons - so it's all user done. Just google 'Gentex compass calibration' or 'Donnelly compass calibration' and you'll find a few hits with the full details.

I have seen the temp sensor ones, but didn't pursue them. The FG doesn't need it, and I don't like the much larger "window" in the mirror surface, but there's nothing stopping you fitting one to a car, as long as you get the correct sensor - there's dedicated pins in the back of the mirror for it, and the pinouts are commonly available online. You can swap them from F to C too.