FIGHT HIGH HEATING OIL prices and save money for other things like paying your mortgage or refinancing your home. Hope this helps:-) Note: Look T THE VIDEO RESPONSES THEY ARE VERY GOOD! This is a prototype easy to build rooftop forced air heater that produces 45 degree increases at a high CFM CFPM rate. This one is made out of cardboard. A real one can be made out of weather proof material COROPLAST.