Product review (5 stars): Awesome Product.  Highly Recommend.
Awesome Product!  In deference to other who have left poor reviews I would say you either had a defective unit or don't understand what this product is.

Review:
The base unit and the remote sensor were packaged well.  I unpacked them and put batteries in both.  I did put a lithium AAA battery in the remote sensor as it is outside and it gets very cold in Wisconsin in the winter.  The unit started working right away.  There was absolutely no calibration or extra step to take.  For the time being I hung the remote sensor with some hard wire form the eve of my house.  The base station is about ten feet away through a brick and wood wall.  I have compared both the inside base station and the outside remote with another digital thermometer and a manual (mercury-like substance that rises in a a glass tube) thermometer.  I have also checked both units with a separate hygrometer  that I have to verify the humidity.  The unit matches to within 1 degree in temp and 1-2 % in humidity!  It really doesn't get much better than that.  What's more, both the temp and the humidity update regularly by the minute or sooner.  There is a good degree of contrast so the numbers are easy to ready in most light settings.  In complete darkness you will need to shine a light on it though.  The display is also visible from a wide range of viewing angles.  You do Not have to look at it straight-on in order to see the numbers.

To recap:  It worked perfectly right out of the box.  No calibration or adjustments necessary.  It is accurate and easy to use.  Great product!!