Funnels intended for use with flammables are fitted with a brass flame arrester that absorbs and dissipates heat, preventing any external ignition source (like sparks from power tools, static electricity or cigarettes) from reaching the drum's flammable contents. Heavy 18-gauge galvanized steel, with electrostatically applied epoxy powder-coat finish, provides durability and chemical resistance. Self-close models have a fusible link that melts at 165ºF (74ºC) shutting the cover automatically in case of a fire to extinguish the flames.