Product review (3 stars): Poor calibration function but it works well generally.
The reading have more than 3.0 degree (Celsius)  difference between internal sensor and the external sensor. There is only one calibration value for the entire temperature range for both sensors, it is impossible to see the accurate temperature reading for both sensors for full range. I need to evaluate the difference for full range and need to put some kind of calculation after exporting the data into an Excel file.  Overall the device works fine. .