Duda Solar 300 Liter SUS304 Passive Water Heater Attached Pressurized Tank Evacuated Tubes Hot Hailstone Resistance: up to &phi;mm (1"), Max Operating Pressure: 100psi, TK-7Y Controller 304 Stainless Steel Outer Shell & Stand, Pressurize tank for domestic water supply, 14mm TU1 Copper Heat Pipes, Winter Resistant 58mm x 1800mm Three-Target Cu/SS-ALN(H)/SS-ALN(L)/ALN Vacuum Tubes, High Boron Silicon 3.3 Glass Sun Absorption Efficiency: 93-96%, Vacuum Rating: Less than 5.0 x 10^3 Pa, Lifespan:70% @ 15 Years Tank Diameter: 460mm (18.1"), Inner Tank Material: SUS304-2B Food Grade stainless steel