material is made up of twin polypropylene walls with thin polypropylene ribs running throughout.The ribs add rigidity along the length of the sheet,while leaving most of the sheet's volume hollow
to reduce weight and save raw materials.It comes in special UV-resistant varieties that will last up to two years outdoors.Manufacturers typically offer a wide variety of colors and thicknesses
(Quite commonly 4, 5 mm).
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