Polycarbonate Crystal Hollow Sheet increases the thermal insulation and higher impact strength which is better than general twin wall polycarbonate sheet,suitable for using in higher thermal insulation applications.Four-wall Hollow Sheet has been specifically designed for simple and fast installation.It won’t crack or split when cut or drilled.The light-weight structure can save more steel skeleton material and also has elegant appearance.Polyrise 4-wall sheet has 8-20mm thickness options with 10 years warranty.