mm of water
The millimeter of water (mmH₂O) is a unit of pressure exerted by a 1 millimeter column of water at 4 degrees Celsius under standard gravity.
Millibar
A millibar (mb) is a metric unit of pressure equal to 100 pascals, or one hectopascal. Standard atmospheric pressure at sea level is 1,013.25 millibars, and weather forecasts quote air pressure in them.