They're called Stability Balls, Exercise Balls and Yoga Balls. Whatever you call them, incorporate a Stability Ball by getfitsource.com into your fitness routine and make your routine more fun and more productive! A Stability Ball is known by many different names depending on geography and manufacturer; it is often referred to as a Swiss Ball, an Exercise Ball, a Gym Ball, a Gymnastic Ball, and a Fit Ball, to name the most common aliases. An inflatable Stability Ball by getfitsource.com is well constructed from top-grade virgin PVC-type plastic and has been tested to a "Burst-Proof" standard.