It is not accurate enough to monitor fermentation temperature; it read 14 degrees lower than two other thermometers I tested against: one was a spirit thermometer and the second was an electronic thermometer (the probe of which I had calibrated in boiling water). All three thermometers were submerged in a large stainless beaker. The water was stirred and the readings were taken after each had reached an end-point (quickly for the electronic probe, but to be sure, I waited an additional 10 minutes to take a reading on the others).
Even if it were accurate enough, it would be difficult to read precisely as the nominal 4" scale covers 200F. As I bought the thermometer from morewinemaking, I had assumed it would be useful for wine, but not, at least the way I know to make wine.
I've made many purchases from this company and this is the first time that I have been let down by the product itself. Excluding this purchase, I would rank it a 5-Star outfit.
I used to use it in my MLT to be able to open the lid and not have to wait for a new temp check to stabilize. I would do a side by side quick calibration to make sure the numbers match and if not, determine a correction factor and keep it in mind for future use. I recently broke mine, but it was to no fault of the fragility of the glass, I just messed up in handling it.
The same situation - bad quality, thermometer was broken when i was getting water to boiling with crashed glass and many little metal balls on the bottom. Fortunately, there was no grain in the mash tun.
I got one of these in a basic starter brewing kit, and it works very well for the price. However, there are a couple problems.
The first one I had broke in the pot randomly, spilling little metal balls in the pot. Luckily I was just getting the water to boil before adding any extract so I was able to dump it, but if that happened when I was further along it would have ruined a batch.
Also, on small pots it doesn't stand up straight (understandable), but the numbers tend to roll downward making it hard to see. Not a huge problem.
Lastly, on larger pots I have found it can be hard to see the end that is floating out of the water with all the steam, so be careful when reaching in to grab it.
It worked as a started thermometer, but now that I upgraded to integrated thermometers I can't see myself every going back to using this.