WaterHog Fashion Commercial-Grade Entrance Mat, Indoor/Outdoor Charcoal Floor Mat 4' Length x 3' Width, Bluestone by M+A Matting Polypropylene fiber system dries quickly and is suitable for outdoor use Unique ridged construction effectively stores dirt and moisture beneath shoe level Exclusive rubber reinforced face nubs prevent pile from crushing in high traffic areas, thereby maintaining high performance and extending product life Not adversely affected by salt or ice melt Certified slip-resistant by the National Floor Safety Institute