A Water & Foam Fire Extinguisher is a multi-purpose fire extinguisher that can be used on Class A and Class B fires. Class A fires are fires involving ordinary combustibles such as wood, paper, and textiles. Class B fires are fires involving flammable liquids such as gasoline, oil, and grease.Water & Foam Fire Extinguishers work by smothering the fire with a blanket of foam. The foam deprives the fire of oxygen, which helps to extinguish it. The water in the foam also helps to cool the fire, which further helps to extinguish it.Water & Foam Fire Extinguishers are a good choice for use in homes, businesses, and vehicles. They are relatively easy to use and they are effective on a variety of fires. However, it is important to note that Water & Foam Fire Extinguishers should not be used on electrical fires or fires involving metals.