I have extremely bad luck when it comes to beverages. I can't even tell you how many times I have knocked over a tumbler or mug. I was very interested in trying this cup holder out since it seems like it would make knocking over a cup an unfortunate thing of the past. It has! It has been at least a month since I last knocked over a cup, thanks to this nifty little cup holder. It clamps firmly onto the edge of a sitting or standing desk and every cup that I have tried so far fits into it perfectly. It has a slot for mug handles. Even tall tumblers with tall straws sticking out of the tops, which I am particularly notorious for knocking over, are no match for this cup holder. Cups stay put. The material it's made from feels strong and durable, and I love that it has a small area for holding small things like paper clips, rubber bands, etc. This is very cool and I definitely recommend it.