Material: Aluminium alloy;Solar vacuum tube with heat pipe;Glass tube dimensions: 58 mm x 1800 mm / 47mm x 1500 mm;Qty of tubes: 15 / 20 / 25/ 30 pieces;Hail resistance: diameter 25 mm;Insulation layer in chest;50mm thickness imported polyurethane, machinery overall for keeping same temperature and high pressure foam;Heat preservation: 72 hours;Max. pressure bearing: 6 - 8 bar;Manifold : red copper;Manifold Casing: aluminium alloy;Max pressure: 10 bar;Working pressure: 1-7 bar;Coating of vacuum tube: ALN/AIN-SS/Cu;Heat Pipe: anti-freezing > -35C;Under CE certification/ ISO9001 / EN-12975;3 years international responsibility for free repairing or exchange due to original quality problems.