ISI marked.  Supply With Wall Bracket. The body of the extinguisher is made of high-quality steel or aluminum, which is designed to withstand high pressure. The inside of the extinguisher is lined with a special coating to prevent corrosion. The extinguishing agent used in Mechanical Foam Type Fire Extinguishers is a special foam concentrate. This foam is designed to quickly smother the fire by forming a blanket over the surface of the burning liquid, cutting off the supply of oxygen to the fire. The nozzle of a Mechanical Foam Type Fire Extinguisher is specially designed to create a gentle and consistent flow of foam, which helps to prevent the fire from spreading. The nozzle can be adjusted to create a straight stream or a wide-angle spray, depending on the situation.