Humidity module for attachment to the testo 625 thermohygrometer and testo radio handles. For use with testo 315-3 CO/CO2 monitor to add the functionality of ambient temperature and humidity measurement. The humidity module can be attached to the handle of the testo 625 thermohygrometer (available to order separately) to enable temperature and humidity measurement in inaccessible places. You can use the humidity module in combination with an appropriate Testo radio handle and measuring instrument (both available to order separately) for wireless measurement. Can be used with the testo 315-3, 625 thermohygrometer, and testo radio probe handles For wireless humidity measurements (with radio handle)