Relieve tired, sore, or achy muscles with the Stress Buster Massage Ball from Ball Dynamics. This little ball is the firmest sensory massage ball available from Ball Dynamics. The Stress Buster Ball helps improve circulation, relieve stress and tension, and is great for self-massage. Simply lie down and place the ball on tense muscles and move around on it, or roll underneath your feet for a great massage. Use after a long day or an intense workout for splendid relief.