Mortar MultiSet Modified Thin-Set Mortar offers good bond strength for tile installation over most surfaces Apply over concrete, cement backerboards and existing ceramic tile Meets ANSI A118.11 when added at required 5 to 1 ratio Protected by MoldGard technology to resist mold and mildew growth Use with vitreous, semi-vitreous or absorptive tile, ceramic, mosaic, quarry, cement, porcelain, brick and mini-brick, precast terrazzo and natural stone Gray 50 lb bag