ARDEX X 77™ MICROTEC® Fiber Reinforced Tile and Stone Mortar is a high-performance, microfiber-reinforced, polymer-modified mortar formulated especially for large format tile installations. Use to install porcelain, glass, quarry, ceramic and most natural stone tiles over interior or exterior concrete and masonry floor and wall surfaces. Also use for interior applications over exterior-grade plywood. ARDEX X 77 is ideal for use in swimming pools and fountains and over in-floor heating systems and is recommended for all tile sizes, including mosaics.