Type 300 Filter Regulator. The Type 300 Instrument Air Filter Regulator is designed to provide clean, accurate air pressure to instruments, valves, and other automatic control equipment. This filter regulator has been proven to provide accurate operating characteristics under variable conditions. Durable materials and a standard epoxy paint finish provide long lasting corrosion resistance in harsh industrial environments. The Type 300 is a quality unit that is ideal as an economical alternative for control of process applications.