Amprobe MANO2-A Differential Pressure Manometer Measures gauge or differential pressure up to 2 pounds per square inch (psi) in heating, ventilation, and air-conditioning (HVAC) applications and in devices with valves and pneumatic controls, such as medical equipment Choice of five units of measurement Hold function keeps a reading on display, even after meter is disconnected or pressure measurement changes Record function stores the maximum and minimum readings in each session to track sudden increases and decreases in pressure Clock keeps track of the time of measurement events so that pressure measurements can be analyzed in relation to other concurrent events, and pressure fluctuation patterns can be spotted