The Testo 420 Differential Pressure Instrument features Bluetooth connectivity which allows for a wide variety of test functions and reporting options using your smart phone or device. The powerful testo 420 App makes testing and reporting versatile, customizable, and convenient. The 420 is a powerful and precise differential pressure instrument with available calculating and reporting functions built-in. When installed on the testo 420 flow hood (not included), this multi-function flow instrument can be tilted or positioned for convenient viewing and handling. View measured data from a remote location wirelessly on a smartphone or tablet (up to 65ft.).