Inches of water
Inches of water (inH₂O) is a pressure unit from the Imperial system. An inch of water is defined as the pressure from a one inch column of water at 4°C (39.2°F) (which is the temperature at which water is densest).
Newtons per meter squared
Newtons per meter squared is the same as Pascals (Pa). It is one Newton of force exerted on an area of one square meter.