Therapy Gel Packs: They can be applied either hot or cold - microwave and freezer safe. Ideal for pain relief: for aches & pains, dental pain, hot flashes, insect bites, joint pains, menstrual cramps, migraines, sinus pressure, sore muscles, etc. Reusable & Long-Lasting: Caldera Hot & Cold Therapy Gel Packs are specially created to be used over and over again. Non-toxic. Made in the USA.