 The most attractive, durable polytarp sails are usually made from a heavier white polytarp material.Generally, polysails are made from white ultraviolet-protected (UV-protected) material that is 12–16 mils (0.30–0.40 mm) thick (1 mil is .001 inches) and weighs about 6–8 ounces per square yard (200-270 grams per square meter) —about twice the weight and thickness of the common colored tarps which usually have no UV protection.The weave density of polyethylene strips in the inner layer determines the quality of the material.