Rotronic ER-15 Thermohygrometer Calibration Device. Calibration Chambers. A small stainless steel airtight chamber, to fit onto humidity probe sensor. Screw-mount accepts humidity calibration capsule contents and a textile pad approved humidity calibration capsules available separately. Humidity Calibration Chambers & Capsules. Humidity probe sensor chamber and capsule system generate a precise humidity value environment for humify meter probe calibration, combinations available for most humidity of probe, diameters and calibration values, capsules accepted within ISO9000, FDA and similar quality systems.