the most prominent feature of my design is a secondary trigger which only applies heat when foam is being dispensed. when foam is dispensed quicky, then the heat needs to be higher to allow time for transfer to the urethane. so i use a rheostat in a dimmer circuit. the main dispensing tube is a direct swap for the stock tube, and it is rifled internally to swirl the urethane in a vortex for better heat distribution. the tube is copper for good heat conduction. the heating wires are distributed so that more heat is concentrated at the outer tip. a thermal cutoff probe is located at the tip to monitor the temperature of the urethane leaving the gun. a bimetal strip within the ceramic probe cuts the electric circuit at a preset 20 degrees celcius. the heating element coils are wrapped into a precut groove for easy assembly and disassembly. there is a glass insulator around the tube to prevent accidental burns. because it is clear, it is easy to tell when the heater is working and the coils will glow brightly when in action. the electronics work on a 12VDC current to be internationallly compatible. the region specific transformer is external, and there is also the option to use an automotive battery directly.