Formulated to create a long-lasting watertight and weatherproof seal with superior flexibility and adhesion to a variety of building materials making it ideal for filling and sealing cracks and gaps. When cured, it is mold and mildew-resistant and will not crack or shrink. Unlike acetoxy silicone sealants, this silicone rubber concrete and masonry sealant is low in odor. Meets ASTM Specification C 920, Class 25, Type S, Grade NS. Color is Gray.