The i-sells digital hygrometer is a simple, accurate and comprehensive way to determine the humidity levels within a property. Easy to read "High" "Low" and "OK" display allows you to easily establish whether or not you are currently in a high or low humidity environment. In addition to this, the current humidity percentage is displayed in large font in the middle of the screen. A "Trendline" allows you to closely monitor if the humidity levels in the property are either: increasing, decreasing or are staying at a steady and consistent level. This is valuable for anyone trying to lower the humidity in their home due to damp or mould growth. The large central temperature gauge is displayed underneath the humidity percentage and can be calibrated to display in either Celsius or Fahrenheit. On either side of both the humidity percentage and temperature, displays are the recent lows and highs of that measurement. This allows you to closely monitor fluctuations between temperature and humidity levels. Features: Indicator of comfort level Temperature and humidity trend line indicator 24hr minimum and maximum temperature/humidity levels Celsius and Fahrenheit option Magnet, hang hole and stand for convenient mounting Specifications: Indoor temperature range within 0 - +50C or 32 - 122F Indoor humidity range within 20-95% RH with +/-5% RH accuracy 24 hours humidity and temperature ranges can be recorded for monitoring purposes Humidity and temperature detection takes place every 15 seconds Temperature and humidity trends detected once every hour. If either temp has an increase or decrease of 1 degree then the trend will show a decreasing trend. this applies to humidity with a deviation of plus or minus 5%. Comfort levels will point to "LOW" when humidity is less than 30%, "OK" when between 30-50% and "HIGH" when above 50%. Supplied with two AAA alkaline batteries