In combination with the testo 660x probe series, the testo 6651 temperature/humidity transmitter meets high demands. It is not possible to solve every measuring problem in air conditioning technology with “simple” temperature/humidity transmitters. We recommend you get the testo 6651 transmitter for special challenges. Combining it with the testo 660x probe series makes it the first choice when it comes to measurement in rooms and also ducts. testo 6651 temperature/humidity transmitter: the wide range of fields of application Stationary measurement of indoor climate conditions: Monitoring of comfortable climate conditions Museums Storing hygroscopic substances Storing electronic components Stationary measurement of production climate conditions: Drying processes/high-humidity processes Food: processing cheese, ripening fruit, drying pasta, conditioning chambers for cold meats Bio research Mushroom cultivation Note: Please keep in mind that you need an attachable probe to commission the transmitter.