1. Solar Keymark,CE,SRCC,SABS 2. Non-pressurized 3. 10 years warrantee 4. 10-15 days delivery 5. OEM available... All stainless steel type compact Non-pressurized Solar Water Heater  Features: This type is a compact non-pressurized system. It is the natural circulation system that works on a light absorption principle. The solar collector converts solar energy into thermal energy, then heat the water step by step. The temperature within the cylinder allows the natural water circulation to operate, transferring the heat water to the top of cylinder and heating the cold water at the bottom at the same time. Description :Inner tank: SUS304/2B 0.41mm Outer tank: SUS304-2B/BAFrame: SUS202/304