Tec7 Pur Pro is a Fire Retardant Class B1, low expansion Gun grade Expanding Foam that uniqually stops expanding when it meets resistance.Tec7 Pur Pro is ideal for filling, sealing, insulaton and prevention of thermal bridges and is soundproof. Tec7 Pur Prpo adheres to ost building materials and can be sanded, painted and plastered after 90 mins. B1 Gun Applied Fire Rated Expanding Foam Stops Expanding when it meets resistance