TheraGear Swiss Ball Pro These exercise balls have become an extremely popular way to increase core balance and abdominal fitness. They are also known as stability balls, fitness balls, balance balls, Pilates balls, body balls, gym balls, or yoga balls. The Theragear Swiss Exercise Pro Ball features extra thick walls, constructed to perform with exceptional durability for your workout. Offers maximum firmness and support. If the ball is punctured it will deflate safely and slowly.