The 3M? Cold/Hot Gel Pack is a flexible, reusable gel pack that can be used for both hot or cold compress therapy. Place in the refrigerator or freezer for cold, microwave for heat. Large sized packs measure 4″ x 10″ and are packaged in sets of two with two covers included. Extra covers for hygienic applications are also available in 100 packs for clinical settings. Ideal for treatment of minor injuries, twists and sprains, these convenient gel-filled pillows are the perfect first aid accessory for the home.