The Aeromat Mini Weight Ball Pairs Are Hand-Held, Ball-Shaped Isotonic Weights A Soft Alternative To Traditional Isotonic Dumbbells Providing Users More Versatility For Strength Training And Rehabilitation Exercises. They Are Unique Because The Size Of The Ball, With A Diameter Of 3.6 Inches, Does Not Increase As Weight Increases, Allowing For A Consistent And Functional Grip. This Allows For Either Unilateral Or Bilateral Exercise Progressions, Either Independently Or With A Partner. Comes In Pairs, Allowing More Versatile Exercises And Additional Resistance With Full Range Of Motion, Making Them Perfect For Overhead Shoulder Rehabilitation, Strengthening Exercises With Both Arms, And More Isometric Training. Isometric Exercise Is A Unique Type Of Strength Training. Instead Of Concentric Or Eccentric Exercises, Which Require You To Move Muscles And Lift And Move, Isometric Exercises Require You To Stay Still. To Achieve An Isometric Exercise With Soft Weights, Hold The Weight In Front Of You Or Off To The Side For As Long As You Can, Keeping Your Back Straight And Focusing On Using Your Shoulder Muscles, Rather Than Your Back Muscles. Once You Can Successfully Perform Your Exercises Without Difficulty, You Know It S Time To Move To The Next Resistance Level. Small Weighted Balls Are Great For Use In Physical Therapy, Rehabilitation, And Strength Training.