Duo-Lock is a needle punched felt surface with a textured rubber lower surface to prevent slipping. * Non-slip for all rugs and all hard floors. Reversible to keep rugs flat on carpet. Duo-Lock does not mark or stain floors. * Contributes to LEED for a greener environment with no chemicals that out gas. * Duo-Lock is Made in the USA - .25 inches thick. Mold, mildew and moth resistant.