A hygrometer is an instrument used to detect the amount of moisture and humidity in the air. This can be useful if you live in a warm or humid climate. If you have a wine cellar. Or you just dig knowing what is going on with the weather. The humidity in your home and office has a direct effect on your health, power bill and damage to your walls and belonging. All of our Fischer Quality German Made Hygrometers have a 2-year Warranty and have FAST FREE SHIPPING Internationally.