Tec7 Pur is a Fire Retardant Class B2 low expansion hand held Expanding Foam that uniqually stops expanding when it meets resistance. Tec7 Pu 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. B2 Straw Applied Fire Rated Expanding Foam Stops Expanding when it meets resistance