Tuff Duck Granite, Grout and Marble Sealer 1 Gallon Stone Tile Maximum protection for Granite, Grout, Marble, Travertine, Limestone, Slate, and even Concrete! Penetrating sealer will not affect the natural appearance of your delicate stones Twice the active ingredient as StoneTech to ensure proper protection with a single coat Protects up to 5 years on interior surfaces and 3 years on exterior surfaces Non-Acidic formula provides coverage for up to 800 square feet