1.Glass vacuum tube solar collector, high temperature,antifreeze,vacuum insulation. 2.Copper heat pipe,Start up quickly,transfers heat quickly, low ... start-up temperature,low temperature resistant 3.Food-grade stainless-steel SUS304 2B inner tank,full ... anti-corrosion function. 6.Gravity assisted heat pipe, unilateral heat transfer,high efficiency,low heat loss. 7. work under pressure ...