The ball was too small to fit inside the hoop after the chair was put together. I tried to use it still but it sits too low and feels like the bottom of the chair is going to pop it. The ball is supposed to rest on the hoop like in the picture, but looks nothing like the picture even after trying to pump more air into it. I sent an email requesting another ball and have not gotten a response. I am not happy as I am working from home now and developing physical complications from sitting at an desk all day.