... vacuum tubes to use long time. Non-pressurized Solar Water Heater TECHNICAL DATAWATER STORAGE TANKSMaterial of out tankHigh quality ... :Stronger galvanized steel / Stainless steel/aluminium alloyBracket angle:0,18,22,38,45 optional, pitched roof, flat roof optional ... specificationCapacityEB3-14φ58mm*1600mm*14130LEB3-16φ58mm*1600mm*16148LEB3-18φ58mm*1600mm*18165lEB3-20φ58mm*1600mm*20185LEB3-22φ58mm* ...