By which I mean the folding contraption with a 'table' and a 'stool'.
As Andy states, it must be sited on level ground; but even this can be a problem.
As the frame of the contraption is all designed to present a flush framework to the floor, the slightest variation in levels of, say, your garage floor can mean that the contraption is supported on the middle of a cross member and disconcertingly rocks when you move around.
I purchase four adjustable feet from Amazon, drilled each corner of the frame and fitted these small 'legs'.
When erected, it may still rock slightly but, once you are seated the frame twists slightly to ensure that all four feet are firmly on the ground.
This only works on uneven 'flat surfaces' If you follow my drift.