This innovative weather station compares indoor and outdoor conditions so to tell you to open or close your windows to achieve optimal indoor comfort. It features a 5 level humidity scale, window status icons, and indoor and outdoor temperature and humidity display. Dimensions: Receiver: 3.72"" x 0.78"" x 6.18"" Sensor: 1.41"" x 0.62"" x 4.03"" All Features: * IN/OUT temperature (°F/°C) with MIN/MAX * IN/OUT humidity (%RH) with MIN/MAX records * 5 Level humidity scale from dry to wet * Dry: below 34 %RH * Comfort/Dry: 35 - 40 %RH * Comfort/Ideal: 41 - 55 %RH * Comfort/Wet: 56 - 64 %RH * Wet: above 65% RH Specifications: * 330 Ft. range * Wireless outdoor temperature range: * -39.8°F to 139.8°F (-39.9°C to 59.9°C) * Indoor temperature range: * 14.1°F to 139.8°F (-9.9°C to 59.9°C) * Outdoor humidity range: 1-99% * Indoor humidity range: 20-95% * Wall hanging or free standing * Up to 12 month battery life * 4 ""AAA"" Alkaline batteries (not included) * IN/OUT temperature with MIN/MAX * IN/OUT humidity with MIN/MAX records * 5 Level humidity scale from dry to wet * 2 Window icons suggest opening or closing windows * Wall hanging or free standing * Uses 4 AAA batteries (not included)