The 12 cm diameter of the MyoSphere makes it ideal to self-massage the large troublesome muscles in the legs (calf and hamstring), hips, gluteals, torso (pecs and obliques), shoulders and upper back. Providing a firm tissue massage, the MyoSphere will satisfy those who wish to achieve a more intense massage experience. Thanks to its unique spherical textured design, the MyoSphere is easy to keep in place, use to apply sustained pressure or roll away with a 360-degree plane of motion. Made from a high density material, the MyoSphere withstands repeated use without losing its shape. How does the MyoSphere work? Using the SMR (Self-Myofascial Release) technique (rolling away or applying sustained pressure to sore areas), the MyoSphere helps to break up tissue adhesions by penetrating through the layers of muscle and fascia.