Abstract: A flexible sheet or garment to be worn on or around the human body, or body member for cooling and having two flexible plastic sheets or films which are joined or adhered to form two tortuous, adjacent, generally co-extensive, non-communicating fluid paths, one of said fluid paths being substantially and permanently filled with a viscous liquid heat transfer media and the other of said fluid paths being in communication with a reservoir of pressurized gas, means between said reservoir and other fluid path for regulating the flow of pressurized gas through said other fluid path and a pressure relief means in said other fluid path and positioned at a point remote from said reservoir to limit the gas pressure and gas flow rate in said other fluid path; and means for holding said sheet or garment in place on or around the human body, or body member.