Reusable Fabric Hot/Cold Therapy Packs can be warmed in the microwave or chilled in the freezer. Gentle to the skin, Fabric Packs do not need to be wrapped in a towel, and even more-they retain cold and heat longer than traditional hot/cold packs. Durable, reusable design offers up to 30 minutes of treatment. For relief of pain from swelling, sprains, bruises, and muscle soreness. Long-lasting, reusable. Non-toxic, biodegradable fill. Alleviate pain from strains, sprains, tendonitis, and injuries - for ankle, arm, back, elbow, headache, knee, neck, shoulder, or wrist.