Have you ever walked in the gym and wondered why there are some stupid giant rubber balls? Well, they are exercise balls and they are not as useless as you thought. In fact, they are a great addition to your workout routine, no matter which type of trainers you are. However, choosing the right ball is not always easy for everyone as there are some factors to consider. Don’t worry, in this article, I’ll bring you the 5 best exercise balls and show you how to buy one.