... 2. PRESSURIZED SOLAR COLLECTORS 3. 24/7 Solar Keymark Vacuum Tube Solar Collector Characteristic:1. Adopts red copper channel, ... independent and efficiently.5. No water flows inside the vacuum tube, no risk of freezing.6. Withstand high water ... Insulation layerCompressed rock wool. Bracket Performance and Specification:BracketIron spray plastic(Aluminum-alloy, stainless steel, optional, will quote per ...