CNBTR  Automatic Timed Water Trank Direct-Acting Drain Valve Electronic Timed Air Compressor Forging Brass 1/2" Hole Diameter AC110V Drain Valve Hole Diameter:1/2", Voltage: AC110V 50Hz The Timer Drain Valve is Used to drain water from your air tank and any other application where you want a timed operation controling fluid to an open end. Removable filter for easy cleaning. Emission time and interval time are controlable .