Replenishing the battery causes the float to rise and releases the valve from its recess. As a result, the water is able to wash around the valve lens and the water stream moves the valve up. Then the water pressure holds the valve lens against the valve-sealing ring and keeps it closed.

• Multi Pressure
  AquaPro's shut-off valve is able to operate with the low gravity pressure created by an elevation of 1.5 m (5 ft) all the way through to the high pressure of 45 psi (3 bar) - the widest range of all available fill systems in the world!
  
  
• High Speed
  AquaPro's shut-off valve has the largest water passage of all watering systems--making it to the fastest!
  
  
• Air Immunity
  AquaPro's shut-off valve is virtually immune to air in the hose system WITHOUT PURGING!
  
  
• Reliable Function
  AquaPro's shut-off valve uses the hydrodynamic and hydrostatic forces of water, always adapting to existing pressure conditions. This makes AquaPro^® more reliable than any other watering system.
  
  
• Precise Filling
  AquaPro's shut-off valve ensures an absolutely precise electrolyte level from the first cell to the last. Every fill cap will stop replenishing exactly when the required electrolyte level is reached in its cell.
  
  
• Incline Tolerance
  AquaPro's shut-off valve works perfectly, even if the battery is 15 degrees out of level, because of the movable linked valve. The user does not have to worry if the vehicle is on an incline or level.
  
  
• Series Connection
  AquaPro's shut-off valve allows the fill caps to be strung together theoretically without limitation. No parallel branches are needed.