The DAFM3B Anemometer/ Psychrometer meter is designed with 6 HVAC/R must have parameters in one instrument. These are included in a portable battery operated instrument for measuring humidity, air temperature, dew point and calculating wet bulb, air velocity and air volume. The sensor is built into the remote fan and is specially protected by a twist cap. While in operation, open the cap for accurate temperature and humidity readings. From the Manufacturer: UEi Test Instruments has over 50 years' experience designing and manufacturing a broad range of award-winning, industry-leading Test and Measurement Tools. Professionals recognize the UEi brand for quality and innovative features designed to solve real-world problems. UEi backs its products with dedicated technical support, service and repair teams.