Mapei UltraFlex-1 Gray Mortar is a 50lb bag of 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 unique dry polymer, resulting in good adhesion to the substrate and tile.FEATURES AND BENEFITS•Polymer-enriched for performance •Good bond strength with plywoodWHERE TO USE•Most interior/exterior residential installations on floors and walls •Most interior/exterior commercial installations on floors •Most interior commercial installations on walls •Installation of ceramic and porcelain tile, quarry tile, pavers, Saltillo tile, and most types of marble, granite and natural stonePrior to beginning your project, please consult the manufacturer's installation guide