The world's most cost effective heater! It runs on the sun and pays for itself in energy savings! This ingenious solar air heater is the perfect way to keep rooms nice & warm without running up your home heating bill. Just place it in a south-facing window and let it go to work. It's solar-powered fan draws cool room air in where it's heated by a grid of sun-heated solar collectors and recirculated back into the room. Without costing you a penny in electricity charges! Supplied hardware. Ideal as supplementary heat or for heating small spaces up to 150 sq. ft. Recommended for single pane windows only. 47"L x 19"W x 2"D.