Air movement test instruments measure air movement, such as velocity and flow, to help ensure optimum performance of HVAC systems. Handheld air velocity meters and anemometers can be brought to onsite locations to measure wind velocity, air speed, and other variables, such as air temperature and relative humidity. Air flow capture hoods measure the volume of air moving through HVAC diffusers, exhausts, and grilles. Air velocity indicators and air velocity transmitters measure air velocity at precise flow rates and temperatures, and can be mounted in hard-to-reach places. Replacement parts and add-on accessories maintain or enhance the performance of air movement test instruments.