solar vacuum tube 1. CE ISO CCC certificate 2. 15 years' gurantee 3. OEM service offered 4. Delivery: within 7 days solar vacuum tube1, Three-target Solar vacuum tube for solar water heater2, ISO900:2000, CE certificate3, 0.91 transmittance of the outer tube Specifications: 1, Vacuum tube is consists of two layer of glass tubes2, ISO900:2000, CE certificate;3, 0.91 transmittance of outer tube4, ...