If you eyed up the flexible spine of the Herman Miller Setu
earlier this week and thought "nice, but I'd like more rotational combination of axial forwards, backwards and sideways movements" then you're obviously bizarrely well-read on ergonomic seating and probably already know what we're about to say. If, however, you know little about pivotal sections but would just like to sit for a few hours without ending up stiff, then Wilkhahn's ON chair
may be the answer. Unlike regular task chairs, which mainly permit forward/backward movement, ON has an artificial hip-joint with "two swing plates that are just as supple as thighs".