A gray, permanently soft, non-toxic compound which will adhere to most clean dry surfaces. It will not adversely affect other plastic materials or corrode metals. It also has no adverse effect to human skin. RAINBOW Duct Seal Putty, 1 lb Net Content, Pack Container, Composition: Polyisobutylene, Carbon Black, Synthetic Polymer, Preservative, Magnesium Aluminum, Silicate, Aluminum Silicate, Calcium Carbonate, Naphthenic Wax, Tall-Oil Rosin, Cellulose Fiber, Solid Form, Dark Gray, 1.78 Specific Gravity, 24 to 120 deg F