I don't have many mugs so I wasn't worried about how many this would hold.  I can fill it with my demitasse and tea cups.  It didn't slide on the 3/4 inch thick shelf I wanted to use.   Definitely measure unless you don't mind screwing it on.  (I did try bending it too. LOL)  So I decided to screw it onto a shelf.  Still it's nice and sturdy for the price.  

Pros: Good price, sturdy
Cons: Wouldn't fit on 3/4 inch thick shelving in kitchen, which is pretty common size.