Ambient Weather WS-HT12 Pocket Temperature and Humidity (Thermo-Hygrometer) Pen The Ambient Weather WS-HT12 is is an affordable, pen-style tester that gives quick, accurate readings of both temperature and humidity simultaneously. Ideal for heating, cooling, ventilation, greenhouse and other applications where temperature and humidity levels are critical. The WS-HT12 is about the size of a cigar and is perfect for humidor monitoring. AAA battery included. Includes 1 year Ambient Weather warranty.