The Dr. Scholl’s® Hot & Cold Massage Ball can be used three ways: 1) Filled with hot tap water to deliver a warming massage, 2) Filled with cold water and frozen to deliver a cooling effect or 3) Empty/as is at room temperature. The package includes one ball with a cap which can be unscrewed using a coin. Dr. Scholl's has been a trusted brand in foot care since 1904 when Dr. William Mathias Scholl, grandson of a cobbler, launched the company under the name Dr. Scholl Inc.<br />