BOSS 333 is ready-to-use, multi-purpose, polyurethane foam that expands to three times its original volume on contact with air. The expanding action fills holes, cracks and gaps more completely than standard caulks. BOSS 333 has excellent insulating properties and superb adhesion to virtually all building materials. • Meets CA-25-4 • UL Classified, Tested to ASTM E-84 • Triple Expanding • Weatherproofs against wind and moisture • Fills gaps, cracks and holes • Seals out insects and pests • Can be sanded, painted and stained • Complies with EPA Method 24 and California Air Resource Board Method 310 • VOC Compliant Uses • Air sealing • Partition walls with ceilings • Through penetrations around cables and pipes • Seams between chimneys, roof protection, roof panels and wall panels