... /CU selectic complex absorptive coating, through the inner layer , vacuum has an unique effect of thermo, with its temperature up ... degree of idle sunning, performing a strong heating ability, Certificate, CE, CCC, ISO 9001, Solar Keymark.Features:1) Highest efficiency2) ... applied to these systems6) Electrical heating element is optionalSpecifications1) Vacuum tube counts 15,16,18,20,22, 24,26,28,302 ...