The standard dome greenhouse coverings are made from 6 Mil Clear Nylon String Reinforced Polyethylene Sheeting. String poly is manufactured from a triple laminate of low density poly, with a special strengthening additive, and is then reinforced with cross tied polyester tire cord. Woven, Reinforced and superior heavy-duty film resists tears in any direction. The polyethylene has a 90% light transmission and 20% light diffusion. Arctic tested to -60.