Mapei 2905723 Ultraflex-1 White Standard Tile Mortar with Polymer 50 lbs - Ultraflex 1 is a standard-grade, single-component, polymer-modified thin-set mortar for most interior and exterior installations of tile. This mortar has an above average content of a unique dry polymer, resulting in good adhesion to the substrate and tile. Ultraflex 1 can be used for both interior and exterior installations of tile in most residential floor and wall applications. In commercial applications, use on interior floor and wall installations and exterior floors. Ultraflex 1 meets or exceeds ANSI A118.4 and ANSI A118.11 requirements when mixed with water.