Corotherm 10mm Clear Twinwall Polycarbonate Roof Sheet 4000mm x 2100mm x 10mmProperties Excellent protection: against hailstones, vandalism and accidental damage. Fine optical clarity: clear material maximises light getting into the conservatory - light transmission of 82%. Insulating glazing: which can achieve a sheet uValue of 3.2 W/mK. Creates: a bright and spacious feeling environment. Maximises: solar gain. Perfect: for sun lovers. Will: require blinds to prevent overheating in the summer months. High strength: weight ratio. Cost effective: as sheet weight is low, support structures can be lighter providing cost effective buildings.Corotherm provides high levels of insulation.