Castle® Z-3™ is a heavy duty, non-paintable undercoat and sound deadener. This is a low cost way to re-coat fender walls and undercarriage. Tough film will not pinhole, sag, or drip in normal application. Z-3™ exceeds US Government specifications for undercoating (TT-C-502A). Z-3™ provides superior protection against salt corrosion. Avoid application of undercoating closer than 12 to 14 inches from entire exhaust system.