Altimeter setting
From FlightSim
Most aircraft altimeters have an adjustment mechanism, a knob to adjust and a readout called a Kollsman Window, which allows the altimeter reading to be adjusted for current barometric pressure, referenced to MSL. The range of this adjustment is typically a very few thousand feet (3,000 perhaps), either side of standard pressure (29.92 in. Hg or 1013 mb).
See also the Wikipedia entry altimeter.


