Permatex Undercoating protects fenders, frames, fuel tanks, door panels, rocker panels, hoods and firewalls against moisture, road salt and corrosion. Body shop proven, this undercoating won't sag or drip and will sound-proof and insulate. Permatex carries a wide selection of undercoating and rust products for auto body along with weatherstrip, trim, headliner and carpet adhesives for interior and trim repairs.