1)high absorption rate 2)long using life Solar collector project:1. tube size: 47*1500, 58*18002. tube quantity: 25,30 piece(vertual rank), 50piece(paralle rank)3. mnifold material: stainless steel, colored steel4. insualtion layer: 3.5-4cm polyurethanebracket : stainless steel, glvanized stee solar water project