Black Jack silicone roof sealant is a white rubber sealant that provides the ultimate waterproofing protection from the elements. This product has exceptional adhesion and flexibility and is compatible with most building materials. Ideal for roof repairs or on new installations of skylights, windows, doors or vents. In hot or cold climates, this waterproof seal will permanently stretch to prevent cracking and peeling. Cured sealant is mold and mildew-resistant.Seals and stops leaksExcellent adhesion, permanently flexibleHeavy-duty repair