... 1, CE, ISO certificates 2, Support OEM project 3, vacuum tube nonpressure 4, 3 years warranty 5, thirteen years service time ... C) Frame: 1.5mmHeat collector: All glass vacuum tube KD-VT-AG 47/1500All glass vacuum tube KD-VT-AG 58/1800A) Coating: Aluminum ... solar water heater, 1 year warranty for automatic controller Packaging: Vacuum tube / carton (for sample order wooden box packing is required), ...