Millenium KB-2001

The height is ajustable by removing the centre pin and wingnut at the crossover point of the legs and putting it thought a different hole, thus allowing the legs to spread out and lower the seat.
The one leg is fixed under the seat while the other clips in place and allows the seat to be collapsed flat. Four rubber tubed-feet hold the seat on my polished floor, without slipping, and the seat is very well padded. The seat covering is PVC, but of a good quality and does not sweat me. Brought one seat for the Tyros and one to go with my other keyboard I gave to my grandchildren. There is a cheaper seat, but you have to make sure it will take your weight, check before buying.

I bought this for my daughter when she plays her keyboard.
Her points were that the stool was pretty comfortable and felt solid and stable. We have very flat floors so I wasn't expecting any wobble.
There's a tiny bit of movement back and forth but we don't have any other stool experience to reference this against. It's really not much though.
Changing the height is a bit of a hassle because you have to undo the bolt at the joint but this is not a regular operation so not a big issue.
The stools' folding action feels nice and solid with a click into place.
Only con she mentioned was that the seat can get quite sweaty over a period of time but this is easily remedied with a small towel folded on the top.
All in all she's happy with this product and I feel that the price is very reasonable. I'm recommending this to others for light to moderate use.