Permatex OPTIMUM BLACK Gasket Maker is a high-performance, single-component, silicone gasket maker designed to provide a reliable seal in extreme conditions. It is ideal for use on aluminum, iron, and steel flanges, and its fast-curing formula ensures a quick and easy seal. This gasket maker is resistant to oils, coolants, and other automotive fluids, making it ideal for a variety of applications. It also has excellent temperature resistance, withstanding temperatures up to 650°F (343°C) for extended periods of time. Permatex OPTIMUM BLACK Gasket Maker is easy to apply and provides a superior seal that will last for years.