Features: 1. Within 5 ~ 200Hz no resonance phenomenon. 2. simple operation without replacement of parts can be divided to control the 1/2 range. 3. Zero adjustment and span adjustment is very simple. 4. can be easily switched between action and reaction, single-acting and double-acting. 5. The connection is very simple lever. 6. fast response and accurate. 7. The air consumption is small, the economy is good. 8. small actuator can also use the orifice of the pilot valve to prevent the hunting phenomenon.