We have purchased a couple of these thermometers and they are excellent/convenient to use. We did find that on BOTH (purchased at different times) that we needed to test them against a digital thermometer to calibrate them for accuracy or boiling water. One was off by 10 degrees and the other by 5 degrees.
You can find out if you need to add/subtract what is shown on the dial by boiling water... should show 212 degrees F. (100 degrees C). Once that minor issue is taken care of, they are excellent to work with. We used two, one for the pot of water, and one for the cheese pot, to monitor temperatures.