Corotherm 4mm Flat Polycarbonate Sheets (Various Sizes) The benefits of using this flat polycarbonate sheet are that it offers a stronger durable material that helps with impact resistance to extreme weather conditions or forcible entry. The product is highly versatile & can be used in a variety of applications that require high performance. Features Colours: Clear Thicknesses: 4mm High impact resistance Dual sided UV protection Lightweight High light transmission Class 1 Fire Rating 10 year warranty