... ,CE,ISO 3.Deliver time:Within 3days 4.Manufacturer evacuated glass tube DescriptionVacuum tube58-1800mm co-axial structure high borosilicate 3.3 ... resistanceDia=25mmGuarantyWater tank for 5 years, tube and frame for 15 years1,vacuum tube length:47/1500mm,58/1800.2,vacuum tubes:15pcs,18pcs ... water is full,it will close the valve automatically evacuated glass tube for solar water heater