Features: 1) Designed to accept mains pressure cold water 2) Superior heat preservation with 50 ~ 65mm polyurethane tank insulation 3) Outer tank material: stainless steel plate or powder coated color steel sheet 4) Inner tank material: 0.5mm thick SUS304 food grade stainless steel plate 5) Frame material: 1.2mm thick all stainless steel 6) Collectors may be connected in series to increase water heating capacity 7) Easy plug-in installation