Image of an air quality monitoring rack consisting of an API T703 Photometric Ozone Calibrator and an API T400 Photometric Ozone Analyzer.
Not sure which one, but one of these blue boxes is on my #BitinList
Either the T703 calibrator had a heavy turn in its calibration curve or the T400 analyzer had some serious flaws... but multiple calibrations didn't "take" and I got 6 hours of OT before I gave up.