I had these on my shopping list since I first heard about them from an MOC member (don't remember whom, but I hope you know who you are).
I finally ordered a pair, received them yesterday and installed them.
If you are looking for some custom fit ($43), outstanding visibility mirrors for your Ford Superduty (1999-2007 and will only work with the big extendable side mirrors with oval shaped cross section arms), then I would recommend these.
They weren't that hard to install and are held on very snugly with screws and nuts and the visibility is outstanding. I haven't towed with these yet, but I can see way down and way up as well as right next to my truck (no blindspot). The mirror is large enough that the convex view is not as distorted like smaller mirrors of this type.
The only drawback is that folding mirrors back into the truck would require me to extend the mirrors, loosen each C-Betr mounting screw, then sliding the mirror further out. Since this is too much of a hassle, I will probably park where I can avoid the folding.
If you are curious or interested, here's the link:
http://qwks.com/C-Betr-Mirror-Set-p-3.html
Thanks, MOC.