A meter to measure air flow is a device used to measure the rate of air flow in a given area. It is typically used to measure the amount of air passing through a ventilation system, such as an HVAC system, and is often used to monitor the performance of the system. The meter measures the velocity of the air and can be used to determine the amount of air being delivered to a given area. It is also used to measure the pressure of the air, which can be used to determine the efficiency of the system. The meter can also be used to measure the temperature of the air, which can be used to determine the efficiency of the system as well. The meter is typically calibrated to measure air flow in cubic feet per minute (CFM).