The analog hygrometer are much more responsive and more accurate than a variety of digital devices. It is important that the instrument should be wrapped before the first use about half an hour in a damp cloth. If after about 98% rel. Displays humidity, it is ready for use. If not, you can adjust the value of a small screw (Instructions). This procedure must be repeated when used indoors every three months. The hygrometer is reliable, but should not be exposed to direct sun for the accuracy, or located in or near the radiator.