Harpster Tarps Heavy Duty Silver Polyethylene Tarps are waterproof, tear and acid resistant. 6.0-ounce per square yard, 11-12 mil thick, 14x14 weave count. Grommets spaced every 18 inches and at all corners providing plenty of tie down options. Silver on both sides providing 100% blockage of the sun's rays and keeping you and your stuff cooler and in the shade!