Solar heating 1. OEM for solar water heater; 2. Economical, Good Quality; ... . Reliable, efficient, tri-element evacuated vacuum tubes;3. Multifunctional: bathing, washing, domestic heating etc;4. Special high quality Insulated material to reducing ... aside hole, the side out of the water holes, electric heating hole.Frame1.2mm thickness Aluminum Alloy/ 1.5mm thickness Galvanized ...