1. CE certificate 2. high pressure 3. easy installation 4. one tube break, still ok 5. high efficiency Features:1) Pressurized tank, working pressure 6 bar, Max resistance 12 bar.2) Reliable and efficient twin-glass solar tubes3) Copper heat pipes for rapid heat transfer ,No water through the tube, So it can good working in winter without freeze.4) Easy plug-in installation.5) Free maintenance.6) ...