This is a great tray if you need to hold anything up to a mic stand or a small similarly cylindrical tube. It's pretty sturdy and stable once it's mounted correctly.
It's the perfect size for a small synth, a vocal effect, or even an iPad.
I use it to hold a small synth (Behringer TD-3) up from my desk using a straight desktop-mounted stand for lights and it does the job really well. Even programming the synth doesn't really upset the tray, and 95% of the (reasonable) wobble comes from the desktop stand itself.