Review on Digital Refrigerator Freezer Thermometer with Max Min Record Function and Large LCD Display - Waterproof Fridge Room Thermometer for Accuracy and Convenience (3) by Kim Adams

I bought these for our freezers to keep an eye on the internal temperature during a power outage. The blocks seemed to work great when I first installed them. A few days later I went to check the freezer temp and the display was blank. I pulled one out thinking the battery was dead and while I was looking for a spare battery the display came back on. The problem was that the temperature displayed was 45 degrees Fahrenheit. Totally useless for tracking low and high temps in the freezer when you need to take it out of the freezer and let the unit warm up for it to show the temp. At this point, I'm using the devices in the refrigeration section and resorting to the frozen quarter water method or another device with an external display. By the way, the freezer was -2 degrees Fahrenheit, which is well within the capabilities of the unit.