Completely undersized plastic

As others have noted here breaks the plastic seat in no time. I have for our children (then 10 and 12 years old and really no heavyweights) bought 2 pieces of these chairs. After a short time the seat was broken on a chair already. Amazon has exchanged the chair without difficulty. Meanwhile, the seat is also broken at the other chair and on the exchange-chair also. If you look at the structure that is not surprising: the actual seat is made of thin plastic with some reinforcing ribs. The seat is screwed onto a smaller metal plate. Where the plastic surface projects beyond the metal plate, it bends due to the unstable material down and breaks with the time.
I was the exchange of suffering and have helped me today itself. The seat has a threaded left and right may be screwed to the presumably armrests on the bottom. Between the seat and the metal plate can push through a flat iron, there is a small cavity. A 35cm long flat bar with two 7mm holes at a distance of 31cm can be seen in these two screw threads with 6mm screws. The flat iron is then incident on the metal plate and preventing a bend of the seat surface. So the chair should still hold for a while, otherwise you would be landed on the garbage.
I would buy this chair ever again.