... Solarkeymark Certificate,CE,ISO9001,ROHS 2.High efficiency Anti-freeze heat pipe swimming pool solar collectors with CE ,SRCC and keymark ... platingAbsorptivityα =0.92~0.96 (AM1.5)Emission ratioEmission: ε=0.04~0.06(80°C±5°C)Vacuum degreeP≤5.0X10 ... (C)30-95CCopper coils size(mm)12mm/16mm/19mm,optionalHeat exchanger materialCopper, stainless steel, optionalFree components:Electric heater, Magnesium rod, T ...