Answer: manometers

AnswerCrossword Clue
MANOMETERSPressure gauges
manometersMANOMETER, an instrument for measuring the pressure of a liquid or gas
manometersAn instrument for measuring the pressure acting on a column of fluid, esp. one with a U-shaped tube of liquid in which a difference in the pressures acting in the two arms of the tube causes the liquid to reach different heights in the two arms