Thanks for the reply Simon. Interesting, I never really considered where the yoke attached to the shaft, I always assumed it would be about centre. Although you haven't seen how low my chair is, it broke a while ago and it's stuck at its lowest point. I guess I don't really have anything to lose as I can always get a bigger chair and mount it on top. I did consider the box after seeing others do it but I don't want to make it permanent as my desk is used for study and other things. I don't know if I could slide it in the keyboard tray and just Velcro it in place, it might be too tall and my keyboard tray is pretty flimsy