Hollow polypropylene tubes are woven together to form an attractive and durable mat. Cleaning is easy with just some water or a few sweeps from a broom. Mildew is never a problem because the woven construction allows the water to drain. Each mat is light and can be folded into a very compact size for easy storage. Does not harm the grass. U.V. Protected. Great for r.v.s, outdoor events, camping, beach, and dog runs. grommets throughout the mat, not just the corners. Comes with free ground stakes and reusable carrying case.