Stay away from this miserable piece of plastic. It slides like crazy, it's cheap, it creaks and wobbles endlessly depending on the weight you put on it. It's not even worth 3 Euros from a Chinese store.

Update: I'm giving it 2 stars instead of 1 because the fact that it wobbles depending on the weight is advertised as a feature. Which it might be. But the fact that it slides surpasses that.

Very good choice even with a few extra money, as it's worth it. It doesn't move from its position even on tiles. The legs stand conveniently while the surface it touches has the appropriate texture. It has 3 heights and different angles to accommodate one's legs. Although the specs state that it goes from 0 to 25 degrees, mine rotates from end to end, without bothering me as I wanted it that way.