Too much typing or clicking on the mouse makes your finger STRESSED. These iron balls are a great stress relief! While rotate repetitively on your hand it can help: ~to relief your stiffness and relax your entire hand ~to improve manual dexterity and strength ~ to improve forearm and shoulder muscles ~to assist in injury recovery or hand therapy Hold 2 with 1 hand and rotate in your palm! Advance users will try not to let the balls touch one another during manipulation. Such users can usually use more than two balls at one time.