Groove-type Seat: Reliable sealing, less torque, long service life Professionally Designed Sealing Surface: Broadside and arc design, suitable for various types of flanges Mid-plummer-block Spliced Pole: Prevention of lower shaft disengaging from body due to frequent vibration Manual Clutch: Automatic switching, more convenient and reliable Safe and Protective Design: Over-torque protection, anti-condensation heater (VA300/VA200) Precise Worm Gear Drive: High transmission torque, self-locking (VA300/VA200) Clear Display of Valve Position: Display of valve position