Be careful with the ball

I had bought the ball for a herniated disc for my office. After 4 weeks of ball - bursting - it with me. The statement a load of 400kg is then also not helpful. Luckily I davongetrgen only a massive Seißbeinprellung. Neither the head nor the disc is in the Explusion what happens.
Seller, packaging and shipping were otherwise lies OK. But it is not funny (except for colleagues) if a, in the truest sense of the word, the chair is pulled away to sit on or explode.