Hard to believe, but these mats will hold up to 1-1/2 gallons of liquid per square yard! The waterproof rubber backing and "water dam" edge keep moisture, mud, and grit contained. Just vacuum clean when dry. Super-tough P.E.T. mats have raised, crushproof nubs to scrape boot bottoms clean. Gripper nubs on bottom keep mats from slipping or skidding. .