Twin-wall hollow polycarbonate sheet 1) Thickness: 4mm.4.5mm,5mm,6mm,8mm,10mm,12mm 2) size: 2100 x 6000mm TRIPLE layer hollow pc sheetTwin-wall hollow polycarbonate sheet(4 ... buildings, departmentstore, hotels, schools, amusement cents, hospital, etc. sound absorption wall for freeways,high speed railways