Features: 1) Inner tank: stainless steel SUS304-0.5mm 2) Vacuum tube:QB-AL-N/AL-47-1500/58-1800 3) Outer tank: painted steel-0.4mm/aluminum-zinc coated steel-0.45mm/stainless steel SUS304 4) insulation :polyurethane 50mm/60mm 5) Frame: coated galvanized steel-1.5mm/stainless steel SUS430-1.5mm 6) Reflector: aluminum component/stainless steel .