Atmotube Plus 

Each sensor was pre-calibrated. Sensors have sophisticated embedded algorithms to perform automatic calibration over time.

Atmotube 1.0 and Atmotube 2.0

Though each Atmotube performs periodical self-calibration, you may need to calibrate your device from time to time. It is very simple, just choose “Recalibrate” command in the Settings menu in your mobile app and follow further instructions.