Duct Sealing Compound, 1 lb block size.Permanently pliable, non-cracking caulking, specially formulated for sealing cable and conduit entries.Easily shaped by hand, workable from 25F to 120F (-4C to 49C). Dielectric strength 110 V/mil (ASTM D149-64). May be painted immediately. Non-toxic, asbestos free.