This do-it-all Remote Thermometer and Humidity Sensor from Acu-Rite is the perfect instrument for monitoring remote conditions either inside or outside your home. The remote sensor may be placed in a weather protected area outside, or on any level of your home. The base unit links to remote sensors, perfect for monitoring another area from one central location. Consider tracking conditions in these spaces: Living space Crawlspace Basement Outdoors The Acu-Rite thermometer comes with one remote sensor. To view data, simply scroll through the channels on the base unit to display the current conditions in each location. This model also includes a self-setting calendar displaying the date, month, weekday, and moon phase. Additional Features Atomic Clock: Automatically adjusts for Daylight Savings Min/Max Memory: Tracks temperature and humidity in each area Alarm: Includes 8 minute snooze function Moon Phase: Displays the moon in its different phases as the month progresses Backlight: Simply press a button for three second backlight Batteries: 2 AA required for the main unit, 2 AA required for each Sensor. Batteries are not included. Specifications Range of Temperature Measurement (Remote Sensor): -4F to 158F (-20C to 70C) Humidity: 20% to 99% Transmission: Up to 100ft, unobstructed, at a frequency of 433 MHZ Clock: WWVB Radio-Controlled, Quartz back-up Battery life: 1 year using fresh alkaline batteries