Manometers and pressure meters perform measurements of pressure, airflow, air velocity, and related system conditions. Digital manometers are portable handheld meters that measure small changes in differential pressure and are commonly used for laboratory testing, field calibration, and HVAC systems. Air-measuring manometer kits combine a digital manometer with necessary components to facilitate measurement and maintenance in HVAC systems. Analog manometers use liquid to read pressure measurements based on fluid displacement. Digital pressure meters measure and record pressure in hydraulic tooling and industrial systems.