Three-Speed Aneroid Barograph records barometric pressure for 1, 7 or 32 days. Quartz controlled chart drive ensures constant chart rotation. Record barometric pressure from sea level to 2000 ft. Bimetal temperature compensation ensures accurate pressure readings. Set chart speed to 1, 7 or 32 days. Uses two C batteries for up to 12 months of continuous operation. Battery condition indicator shows when to change batteries. Housing is made of corrosion-resistant acrylic plastic. Includes pen and 1-day rotation chart. Dimensions: 13.25"W x 11.5"H x 5.875"D. Shpg wt 9 lbs.