Well, while we're on the subject...
The last convex mirror I ordered from Sierra Madre turned out to be a standard mirror in a box labelled 'convex'. I compared it to the first 'convex' mirror I got from them and the reflected image wasn't the expected wide angle view.
I returned it and they sent me a replacement that WAS a convex mirror.
So maybe the lesson is that either the mirror supplier's or Sierra Madre's QC ain't what it should be. In any case, caveat emptor.