Usage Tips:Multiple Placement : This humidistat has 2 placement - Tabletop Stand and Magnetic Back place the wall thermometer anywhere you wish such as humidors greenhouse garden gellar closet guitar case High & Low Records: This hygrometer digital thermometer displays high/low temperature and humidity levels to allow you to make proper comparisons using your environmnet's data High Accuracy & Quick Refresh Rate: This inside thermometer features a high accuracy of 5%RH and 1.8F, making it Perfect for measuring fluctuating readings like those found in a greenhouse; Data measurements are updated every 10 seconds to give you the latest updates on your environment 12-18 Months Long-life Batteries: Each small temperature and humidity gauge is powered by one long-life CR2032 button cell battery(without battery), easy to buy and replace, which is already installed in the thermometer humidity monitor. size: 5.7 x 4cm Material: plastic colour: Black Package Contents: 4 x hygrometer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.