Order this Mapei 50 lb. Porcelain Gray Thinset Tile Mortar for delivery to your job site. For use with porcelain, ceramic, natural stone, glass and mosaic tiles with grout joint widths from 1/16-in to 1/8-in. For application in submerged conditions (swimming pools, spas, water features and fountains) once fully cured (after 21 days). Contains BioBlock technology for mold and mildew resistance.