Oakton* Wall-Mount Thermohygrometers

Analog model monitors humidity and temperature without the need for batteries or power, features an alcohol-filled thermometer with °F/°C scale and a synthetic hair bundle RH sensor.
Deluxe model features a human hair bundle humidity sensor and a digital temperature sensor and monitors both humidity and temperature while remaining accurate and stable, without maintenance or adjustments. Analog humidity display and 0.5 in. LCD temperature display (deluxe model). Temperature readout can be displayed in °C or °F. Corrosion-resistant plastic housing. Comes supplied with one 1.5V AA battery.