Fast acting heat pad provides 12 hours of pain relief. Soothes and comforts sore, aching muscles and relieves back and joint pain. Adhesive backing for peel and stick placement on underclothes. Exclusive formula works with your own circulation to spread the warmth. Air-activated, odorless and non-medicated. Product is supplied as a pack of 4 treatments, 6 shrink-wrapped boxes (24 treatments) and a case of 48 boxes (192 treatments). Pad measures 3.75" x 5.125". Disposable, single use only.