4 inch x 22 inch. Microwave activated. Deep penetrating pain relief. Provides fast relief from: body aches & pains, cold & flu symptoms, headaches & tension. Relieves pain naturally. Doctor recommended. How it works: The ThermalOn Compress contains special patent pending hydro pearls that continuously absorb and store water molecules from the air. There is no need to add water. When microwaved the absorbed water is released as clean soothing moist heat. Microwave activated moist heat. A ThermalOn moist heat therapy treatment provides deep penetrating, temporary relief from your pain. It relaxes and soothes, alleviating the pain associated with muscle and body aches caused by colds or the flu. Also use for soothing cold. Fast acting natural relief. We believe pain should not get in the way of living life to its fullest. Since our inception in 1986, our mission has been to provide natural relief from pain that is safe, effective and easy to use. Our products are used in clinics, hospitals and homes around the world. Naturally hydrating. Non-allergenic. Odor free. Washable & reusable. Patent pending hydro pearls. Moisture is continuously absorbed from the air and released as deeply penetrating moist heat when microwaved. Use ThermalOn and experience hours of relief! Made in China.