Gardner Bender Electrical Duct Seal is a versatile gray mastic designed for hand application to effectively seal irregular openings between materials such as metal, masonry, and wood in entrances into foundations and structures. This durable sealant protects against the intrusion of water, dust, and insects while also providing vibration dampening benefits. It remains nonhardening, nonshrinking, noncorrosive, and nonstaining, ensuring long-lasting performance without toxicity concerns. Suitable for indoor use, it operates within a temperature range of 20 to 200 degrees Fahrenheit and is applied between 60 and 90 degrees Fahrenheit. The sealant is made from a butyl rubber composite, ing permanent flexibility, heat resistance up to 350 degrees Fahrenheit, and resistance to moisture, mold, and mildew. Please note that this product is not paintable, tintable, or stainable. Packaged in a convenient 1-pound bag, it provides a reliable solution for sealing and protecting various structural openings. Model Number: DS-110N