These are the gel pads that can be heated or chilled again and again to provide relief from muscle strains, inflammation, and arthritis pain. Filled with a non-toxic crystal solution, a click of a floating interior disk activates a chemical reaction that instantly generates heat to loosen tight muscles and boost circulation to promote healing. For soothing cold therapy on painful or swollen areas, simply chill the pads in the refrigerator for 2-3 hours. They are easily recharged for subsequent hot or cold treatments by submerging in boiling water until the crystals dissolve. Set includes a contoured neck and shoulder pad, a 15 1/2" x 5" rectangular back pad with pouch for lower back or leg, and two pocket pads for targeted treatment. (6 lbs.)