The gun style air heater is the third type of direct fired air heater manufactured by Stelter & Brinck, designed for applications with dirty or low-oxygen air streams. It provides the highest mass flows and air temperatures among the three styles and is used in industries such as annealing, metal and glass curing, and drying processes. These heaters can be configured to operate on various fuels, including gaseous fuels and different types of oil.