"TILEFLEX PLUS" GRAY THIN SET MORTAR; Portland cement based thinnest mortar for setting of floor and wall tiles for interior applications. Due to its self-drying Portland cement formulation, Marble Flex will not contribute moisture to marble or stone tile, making it suited for use with moisture-sensitive tile and stone. The quick drying formula allows tile and stone to be grouted in only 2 hours. For the installation of porcelain, quarry, stone, ceramic and mosaic tile over most interior and exterior surfaces. 50 lb. will cover 90 to 100 sq. ft. when using a 1/4" x 1/4" x 1/4" square notched trowel. Gray color Do not expose to freezing. Use clean, damp cloth for clean up. If material dries, use mechanical means to remove. 25 lb. box.