... SUS304/aluminum alloy, 1.5mmInsulation: polyurethane frothing, 50mmVacuum tube: AL/N coating, 47*1500/58*1800mmAccessories: MG rod, electrical heating ... different density between cold and hot water, there will be a natural circulation in the tube, and hot water will float back to ... inner tank and outer tank can keep the temperature of hot water for about 2 days without any sunshine, consumer can enjoy ...