Duct Seal (sealing compound), 1 pound package. Seals irregular openings from air, dust, or water. Non-hardening sealant that adheres to metal, masonry, wood or plastic. Provides vibration dampening. Safe and easy to use, non-corrosive, non-toxic, no asbestos, will not stain or harm hands, and no unpleasant odor. Dielectric strength is 200 Volts per .001 inch of thickness, minimum 0.030 inch sample thickness.