FREE SHIPPING! For optimized light transmission and durability our 4 year 6 mil clear is perfect for the job. Our clear greenhouse plastic is a true 6 mil, not rounded up. It is perfect for germination and early promotion of growth. In high UV areas our 6 mil 4 year clear does the job. Our factory uses more UV Protection for longer film life. it gives optimum light transmission 90%+ so it lets in more direct growing light, while still keeping harmful UV rays out.