12 Mil is a Heavy Duty Premium Poly Tarp is made of tough, durable, and versatile material for on the go coverage including temporary car, boat, truck, and RV coverage, makeshift shelters, keeping firewood dry, and providing temporary shade Provides emergency coverage like on a damaged roof after a storm. The uses for a heavy duty tarp are nearly endless - always a great idea to keep one on hand, whether at home, at a campsite, or just out and about.