The synthetic resin lens has a function to generate heat by selectively absorbing infrared rays with wavelengths of 780 to 3000 nm. The reinforcing component is resistant to damage from compressive forces. A flow valve 76, operable by the user, regulates the flow of pressurized gas from a pressurized gas source through gas flow conduit 50. Two electrode layers are formed on the two sides of the insulating substrate and extend upwardly and downwardly to the upper and lower surface of the insulating substrate. The web of fabric is cut, thereby defining discrete garment-sized pieces.