1. Pilot oriented mode: Internal pilot or external pilot. 2. Structure in sliding column mode: good tightness and sensitive reaction. 3. Three position solenoid valves have three kinds of central function for your choice. 4. Double control solenoid valves have memory function. 5. Internal hole adopts special processing technology which has little attrition friction low start pressure and long service life. 6. No need to add oil for lubrication. 7. It is available to form integrated valve group with the base to save installation space. 8. Affiliated manual devices are equipped to facilitate installation and debugging. 9. Several standard voltage grades are optional.