We received two of these polystyrene chairs and found the assembly to be nearly impossible.  It has taken many hours for us to assemble one chair because the polystyrene is extremely hard and therefore extremely difficult to  get screws to insert properly, even with a powerful electric drill driver.  Wood has a degree of flexibility which allows screws to begin insertion and tighten to the maximum point.  I would recommend buying wood chairs which will be much easier to assemble and probably last with proper care just about as well.