MAPEI 11250000 Ultraflex LFT Gray Thin-Set Tile Mortar with Polymer 50 lbs - Ultraflex LFT is a premium, non-sag, large and heavy tile mortar and thin-set mortar. It is designed for large format and heavy tile and stone for interior/exterior floors, walls and countertop installations. This mortar has a high content of unique dry polymer, resulting in excellent adhesion to the substrate and tile. It is formulated with Easy Glide Technology for ease of application.