Provides up to 30 minutes of cold therapy * Clay inside / urethane outside *Institutional grade packs are made of durable heavy-duty urethane exterior which can be chilled to a lower temperature than other packs and a bentonite clay interior * Chilled pack should be wrapped in towel before applying to treatment area * Notice to California Consumers: WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm *