Everything Yoga Fitness Ball Base Storing Yoga Balance/Fitness Ball in a classroom or storage area can be a little tricky without our handy Fitness Ball Base. The Fitness Ball Base is easy-to-assemble, and is designed to be used with any size Fitness Ball. Simply place the ball on the base and you will no longer have your stock of Fitness Balls rolling all over your studio! These Ball Bases can also be used in class when you need the Fitness Ball to be stable.