Marlon 16mm Clear Triplewall Polycarbonate Roof Sheet 4000mm x 900mm x 16mmProperties Excellent protection: against hailstones, vandalism and accidental damage. Fine optical clarity: clear material maximises light getting into the conservatory - light transmission of 77%. 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.