These ones on the eBay image link, and mentioned by planenut in the original post, are both convex.
Just fitted a pair, the mounting stem is only M8 though but with a large spreader washer. The near/passenger side one is a great improvement over the original. The drivers one although equally vibration free doesn't give such a good view directly behind the car, given the much shorter stem.
Might consider a central mirror as I have a Fairbourne screen.