I had barely begun using it when I decided that I didn't trust the entire batteries, so I put in Duracell.
You can probably imagine how to operate it from the instructions: insert the batteries, point to the green dot on your forehead between your eyebrows, press the button, and that's all there is to it; it will vibrate and display the temperature in a split second.
I did a self-test and found that this one (forehead) was 36.8, whereas Mercury (armpit, 5 minute measurement), was 36.9.
When…