The Thera-Band® Standard Exercise Balls are used to strengthen muscles to improve posture and help prevent back pain.  These exercise balls help improve core stabilization by training the muscles of the spinal column as the body works to stay in balance. Ideal for exercises involving flexion, extension, equilibrium reactions and postural adjustments. Each exercise ball comes with two plugs and an inflation adapter, along with the Thera-Band® Exercise Ball Guide Poster detailing 24 exercises. Available in five sizes to allow for user height variations.