(Product Size: 4.5 Cm * 4.5 Cm,If The Device Has A Black Screen, You Can Open The Back Cover To Replace The Battery.)Mini Digital Thermometer LCD Digital Temperature Sensor Humidity Meter Thermometer Indoor Room Home Use Digital Climate Control Gauge, Temperature And Humidity Sensor, Thermometer With Humidity Display, Digital Home Humidity Gauge, Indoor Temperature And Humidity Monitor, Digital Hygrometer Thermometer (The Back Cover Can Be Removed To Replace The Battery.)