This BLET humimeter has following features : calibration HR : 10 à 90% à +/- 1,5%HR à 25°C ; Calibration T : +/-0,3°C ; Calibration wood water content: 5-15%, +/-0,5% à 25°C ; Hold function, cylindraical probe length 105mm diameter 12mm in plastic, temperature in °C ou °F.