This isn't a very expensive seat, so don't expect top quality. However I have to say that I'm having problems when adjusting height (I do this regularly, using this as a guitar practice, and keyboard playing stool for which I set different heights), and at times the seat comes loose, which you can easily tighten again, but it's just a bit anoying and shouldn't happen. The back rest is a little loose too.
Will probably look at another stool at some point.