... lake,Haiyan,Zhejiang,covers an area of 51,000 square meters. Our main produces including:all-glass vacuum tubes,solar water heaters ... industrial chain,output reaches 500,000 sets of solar water heaters,and the all-glass vacuum tube at 6,000,000 pcs ... with copper heat pipeMaterial and Major Element:1. Material of Vacuum Tube: Borosilicate glass 3.3 ,coating: Al/N/Al OR Cu SS-ALN(H ...