Detailed products description: 1. Certificate: Solar keymark. SRCC. Watermark, Standardmark 2. non-pressure solar water heater 3. 15 years of lifetime 4. high efficiency and good heat conductivity 5. intelligent control ,display the temperature all the time. Specification: Storage tank volume Outer casing: aluminium alloy thickness :0.5mm Inter tank: SUS304 2b stainless steel Insulation layer: polyurethane foam /rock wool for optional Inlet and outlet: SUS304 2b Heat preservation: 72 hours Welding: Arg welding Vacuum tube Number of tube: 20L ,24L,26L,28L,32L for optional Tube length: 47*1500/58*1800/47*1800 for optional Heat absorption rate : 91% Thermal damage rate: ULT =0.82W/(m2) Coating of vacuum tube: AL/N/AL Heat pipe: anti-freeszing>-35 Hail resistance: 25mm Working pressure: 6bar Max test pressure:12bar Max working temperature: 280C Tube holder: UV stabilized nylon Support Aluminum alloy.