Home weather stations include hygrometers, thermometers, barographs, and barometers. Many humidors use hygrometers to monitor their humidity levels. They made thermometers, hygrometers, and measured wind speed and wind direction. More specialized retailers might sell&colon; ashtrays, humidification devices, hygrometers, humidors, cigar cutters, and more. Chilled mirror dewpoint hygrometers are some of the most precise instruments commonly available. Various researchers have investigated the use of saturated salt solutions for calibrating hygrometers. In thermal hygrometers, the change in thermal conductivity of air due to humidity is measured. Lithium chloride is used as a relative humidity standard in the calibration of hygrometers. Devices called hygrometers are used to measure dew point over a wide range of temperatures. Dew point hygrometers work by placing a mirror over a closed sample chamber. Regardless, digital hygrometers tend to be more accurate when compared to the analogue ones. The vapor content of air is measured with devices known as hygrometers. Capacitance hygrometers consist of two charged plates separated by a polymer membrane dielectric. Inexpensive dial-type hygrometers make use of this principle using a coiled strip. Humidistats employ hygrometers but are not the same.