AquaShield Squares Boot Tray, 15 by 36-Inch, Medium Grey Unique ridged construction effectively removes and traps dirt and moisture Molded design will not crush or breakdown over time or use Anti-Static, 100-percent premium polypropylene fiber face will not mildew, mold or rot Made with commercial grade SBR rubber backing Waterguard mats are certified slip resistant by the national floor safety institute