This chair is a piece of junk.  Poor design, poor engineering, components don't line up making assembly difficult.  And to top it off, upon opening the box, one of the casters was broken.  The directions were limited and confusing (es: how much should the ball be inflated?).  If not for being an Engineer, I would not have been able to assemble this chair.  If I could give it 0 stars I would.