Hygrothermograph records temperature, humidity and dew point. Data is digitally displayed and graphed on 6in (152mm) circular charts with selectable speeds. Includes temperature/ humidity sensor and sixty assorted charts. Operates on standard AC power, with 48 hours of battery backup using 8 AA alkaline batteries (not included). MAA-80 is a package of 60 7-day, 40°—110°F temperature charts. Other charts are available upon request.