Marlon 25mm Clear Multiwall Polycarbonate Roof Sheet 4000mm x 2100mm x 25mmProperties High impact resistance: up to 200 times greater than glass. Excellent protection: against hailstones, vandalism and accidental damage. Insulating glazing: which can achieve a sheet uValue of 1.6 W/mK. Lightweight: in nature, compared to single or double glass glazing. Eliminates: harmful UV solar radiation - up to 98%. Fine optical clarity: clear material maximises light getting into the conservatory - light transmission of 68%. Creates: a bright and spacious feeling environment. Maximises: solar gain. Perfect: for sun lovers. Will: require blinds to prevent overheating in the summer months. Up to "Class 1" fire rating: polycarbonate is a self-extinguishing material which will melt away from the flames, stopping as soon as the source is removed. Note: 6mm Twinwall does not have a Class 1 fire rating. High strength: weight ratio. Cost effective: as sheet weight is low, support structures can be lighter providing cost effective buildings.Marlon provides high levels of insulation.