This barometer uses a French-made, aneroid barometer movement with pointer needle to indicate current barometric pressure over a scale of 27.5" - 31.5" of mercury. Accurate to 0.08", this is a fully self-contained instrument that requires no external sensor or power supply. This beautiful weather instrument will make a great addition to any room in your home. This barometer is handcrafted in the United States and includes a 5-year limited warranty.