When many chairs have to be stacked on top of each other or when they have to be pulled out one by one, the hole is made so that there is no trouble when folding or pulling out due to the pressure of the air.
Otherwise, due to the pressure of the air, when the chair is pulled, the air becomes tight in the empty space and it becomes difficult to pull it, while when the chair is placed, the air is filled and there is no place to escape, because the chair does not fall flat.
