"At first, I was a bit skeptical of a thermometer that is stuck on to the outside of the aquarium. However, it has proven to be surprisingly accurate, and in fact very easy to read. The only reason why I didn't give it five paws is because the temperature range isn't very wide (the vertical one only goes up to 82 degrees). Other than that, it is very unobtrusive and does the job it is designed to do. I recommend it."