"Heat Treat 12+ Hour Adhesive Personal Heating Patches 4"" X 5"" Heat Treat Therapeutic Adhesive Personal Heating Pads for muscle and arthritis pain ( 4 per pack ). Convenient heat for back, knee, shoulder - anywhere. Each pad lasts for 12+ Hours. Thin, flexible design provides discreet, comfortable heat. Commended for 'Ease of Use' by the Arthritis Foundation."