[markem]

In a quick google search, I found several sites that claim the Calibur III to not have a calibration ability. Several people recommended using Boveda bags. I have a setup that also doesn't have calibration. What I do is compare it to a calibrated source (like a boveda bag) and then write the + or - on the device (white athletic tape and a sharpie works great). That's work well for me for over 10 years.