I have chewys extenders and although I am happy with them
they still don't address the problem successfully, they're just a small improvement.
These mirrors do appear to solve the problem BUT with a pinch bolt linkage half way out the arm how stable will they be
especially at 70+ MPH when you REALLY do want to know who's following you
I hope you get them and answer this question in the positive as I would definately get a pair if I was buying in confidence.