Detailed Product Description:Diameter 58mm Length 1800mm Quantity 20pcs capacity 200L copper coil 12*0.8mm 1.The material for inner tank, is stainless steel 304/2B,out tank and frame is colour steel. 2.Heat insulation of water tanks adopts polu\yurethane foam,thickness is 55mm. 3.Silicon rings to connects and seal them. 4.The tubes and supports are adjustable,power bearing is average,and can assure the vacuum tubes to use long time. 5.Whole glass vacuum tubes adopt super hardborax and slilica glass. 6.Absorb rate:=93,thermal radiation rate:6(100). 7.Resist 25mm hail,using life can last 15 years. 8.If you use electrical appliance to aid heating,to switch off the power supple before bathing. If you are interested in our products, you can come to our official website, official website of the above can also contact information to understand the products you need more information. http://www.china-solar-water-heater-product.com Nature Solar Energy CO., Ltd.is specialized in producing Solar collector with heat pipe, solar water heaters,solar system,SHCMV tubes and Solar Parts and their accessories. We passed the ISO9001: 2000 and CE marking. We have high quality products, our technology is leading, our price is cheap, we can fast delivery. Through natural circulation or forced circulation, but will heat the water storage box.