I now have 2 Symple Stuff ball chairs one with arms and one without. I love them. They are fun to sit on and have a lot of cushion, so I find that they are more comfortable to sit in for long periods of time than a standard office chair. You can make them firmer or softer by the amount of air you put in. They also get a lot of comments and people want to try them out, then get one! The only negative is that they are not very heavy duty. But they are adequate for my use.