Floor Pro 565 Self-Leveling Underlayment, 40-Lbs.Floorpro, 40 lb, #565, self leveling underlayment, specially formulated, Portland cement based, self leveling underlayment used to smooth & flatten interior surfaces prior to the installation of floor covering, due to its unique leveling & drying characteristics it allows floor covering installation to proceed in as little as 6 hours, coverage 43 sqft per 40 lb bag at 1 8" thickness, install from featheredge up to 5" thick.