This 6-millimeter Clear 4-by-8-foot Twinwall Polycarbonate Sheet is custom cut from a 48-foot master sheet and has 82 percent light transmission. Polycarbonate multiwall sheets offer a high degree of light transmittance while blocit harmful UV rays. Multiwall sheets also offer excellent thermal insulation properties. Lightweight, yet 10 times stronger than acrylic and 200 times stronger than