... frame in surround. Hollow glass is made of two or several pieces of glass composited, separated by frame ... so that have dry air of glass layer. This kind of glass have sound insulation, heat insulation, keep ... hospital, meeting room,etc.substrate:float glass, laminated glass, tempered glass, LOW-E glass, ground glass, coated glass, tempered coated glass, colored glass, amberina,etc.thickness:5mm, 6mm ...