Roc-Kloth is a super-tough, 3-1/2 oz. polypropylene fabric, specially designed for use beneath crushed stone, gravel and paving stones. It suppresses weed growth while allowing air, water and nutrients to pass through. Chemical-free weed control Just cut with scissors to fit Allows air, water and nutrients to pass through Holds up to sharp or abrasive rocks Keeps ants and other insects from moving soil underneath Can be used behind retaining walls, too 4' W x 50' L Made of polypropylene