Essential for monitoring the temperature inside an incubator. Mercury-free thermometer comes mounted on a clear Mylar sheet to keep it on top of the eggs for easy viewing. Easy-to-read graduation marks can be seen through the incubator window. Mercury free Mounted on a clear Mylar sheet to keep it on top of the eggs Measures 4.5 inch wide by 5.5 inch high Essential for monitoring the temperature inside an incubator Easy-to-read graduation marks