Abstract: This invention is a flexible heater or cooler which includes a flexible, conformal, thermally conductive container filled with thermally conductive material. A thermal element within the container or in contact with the outside of the container provides heat to the container or removes heat from the container. The thermal element is powered by a low voltage direct current electrical source. A sensor for determining the temperature of the thermally conductive material is also included. The thermal element, electrical source, and sensor are in communication by connectors with a solid state continuous temperature controller. In operation, the electrical source provides power to the thermal element, thereby heating or cooling the thermally conductive material within the container. The temperature in the container is determined by the sensor and the controller controls the power delivery to the thermal element in response to the setting on the controller and the temperature in the container.