The Deltaphase Isothermal Pad is based on the thermodynamic principle that a heat releasing phase change is isothermal, that is: that it occurs at constant temperature. A unique chemical solution is contained within a durable pouch. At room temperature this solution is in solid form. When heated to 39° using a microwave, water bath or heated oven the solution becomes fluid and the pad is ready for use.
The pad acts as a source of heat, but cannot overheat once it has reached its phase change. The pad can maintain body temperature for approximately 3 hours. No electricity, no control box, no wires.