Our AD-1251 Airflow Probe includes a Differential Pressure Transducer (DPT) and is designed to provide accurate and energy efficient air flow monitoring at all times. Engineered specifically to measure air flow in duct applications, the AD-1251 functions as a differential pressure air measuring device that monitors air flow from 400 to 5,000 feet per minute (fpm). The AD-1251 is versatile and can be used in horizontal or vertical applications. When ordered with an air straightener, it is automatically positioned vertically.