333 Polyurethane Expanding Foam is a versatile construction sealer that expands up to three times its original volume upon exposure to air. Designed to fill holes, cracks, and gaps more effectively than standard caulks, it provides excellent insulation and strong adhesion to a wide range of building materials. This expanding foam is ideal for sealing partition walls, cable and pipe penetrations, chimney seams, roof protection, and wall panels. Certified UL Classified and tested to ASTM E-8 standards, it ensures reliable performance in various construction applications. Available in convenient 750 ml cans.