This set allows you to do all relevant measurements in the ventilation duct and the air/Ceiling outlet! The set includes a climate meter testo 440 dP including differential pressure sensor as well as the 100 mm vane probe head and hot-wire probe head (Ø 9 mm) for attaching to the supplied universal Bluetooth handle. For more comfortable measurements can both probe heads with the included in the set telescopic are combined. To Set a suitable combination case included.The meter has a large, illuminated color display and has a structured measurement menu by pressing and specific temporal averaging, average volume flow, current measured value, as well as min/max values are displayed. You can also dimension and geometry of the channel cross-section must be entered to calculate an exact calculation of the volume flow. Other measurement menus as long-term measurement and volume flow measurement with funnel are also possible.The testo 440 meter collects and evaluates your measurement data and