Extech is a go-to resource for thousands of airflow meter users around the world. Whether you are just learning how to measure air flow or you are an experienced HVAC technician, indoor air quality technician, or energy efficiency consultant, our meters provide air velocity and air volume flow readings as well as useful indoor air quality metrics. CFM? Ft/min? Temperature? We have you covered. Plus, available meters also measure relative humidity, wet bulb, dew point, and carbon monoxide.