HeatWraps with ThermaCareTechnology's patented Heat Cells use controlled, deep penetrating therapeutic heat to provide back pain relief for up to 16 hours. By using a combination of ingredients that react when exposed to oxygen, the HeatWraps are active for 8 hours, and you can feel the benefit of heat therapy for another 8 hours, for up to 16 hours of back pain relief. HeatWraps with Thermacare Technology also help relax, soothe and unlock tight muscles. HeatWraps with patented heat cell technology are the #1 selling non-medicated heat wraps worldwide* Provide up to 16 hours of back pain relief** Speed up the body's natural healing process Are clinically proven to improve flexibility and mobility * Includes Thermacare brand outside Canada ** 8 hours while you wear the wrap and up to 8 hours after you take it off.