Records temperature and humidity on 1 or 3 month rotation for months of unattended monitoring. Quartz-controlled strip chart drive consistently rotates chart drum even when batteries are weak. Range is 5 to 90% RH with accuracy of ±3% from 10 to 90% RH (1% chart graduations). Temperature range is -20 to 50°C with accuracy of ±1°C (1°C chart graduations). Corrosion-resistant case features a tinted cover for easy viewing. Operates on one C battery for up to six months continuous use. Built-in battery test indicates battery condition with one button press. Includes red and blue pens, battery, and one roll of 1-month chart paper. Dimensions: 13.25"W x 11.5"H x 5.125"D. Shpg wt 10 lbs.