3-3/4 in x 5 in. Air activated. Lasts up to 8 hours. Applies directly to skin. Safety tested. Multipurpose muscle & joint heat therapy. Odor free. WellPatch Warming Pain Relief Patch is a safe, odorless warming therapy that provides soothing relief from minor aches, pains, and stiffness of muscles and joints. This comfortable heating patch applies directly to the skin and can be worn unnoticed under clothing as you go about your daily routine. Made in Japan.