My father gets cold very easy and last year he tried the hand warmer packs that are air activated, but this one is a larger patch which adhered to his lower back. I think it is designed for people with lower back pain but he told me it was the best thing he had ever used to keep his entire body warm. I personally find the hand warmer packets are that little piece on top of good boots and socks, plus layered clothing that can make a miserably cold sit very enjoyable. That plus a fleece head sock over your hat.