Our MH-38 Solar Water Heating Panel, functions the same way as our other panels. Our panel is made of lightweight aluminum, both the sides and the backing have been Powder Coated white, to prevent corrosion. The front is Twinwall UV-Stabilized Polycarbonate Glazing, the same material used for bulletproof windows, lightweight and extremely strong. What makes this panel different than our SW-38 Home Use Panel is the Zinc-Phosphate Internal Coating making it perfect for a saltwater/ocean environment. The panel is also silicon sealed throughout. The light weight of the panel, 12 lbs. is perfect for a boat or catamaran. The compactness of the panel, 2ft/2ft makes it easy to use even in the smallest of spaces.