We were so worried about getting the water too hot or having it too cold when we gave our son his first bath. We didn't know what temperature to have the water at, babies are very sensitive to being in too hot or too cold water. This bath thermometer washed away our worries. We put some water in the tub and placed it in...after a couple seconds it will begin to beep, and then it should stop if the temperature is right. If it's too cold it should beep slower, and if it's too hot it should beep more rapidly. It took us awhile to realize there were two different speeds of beeping. Then, we would add more hot or cold water as needed to get the temperature just right. When the temperature is within the correct range, around 95-100 degress I believe???...the beeping would cease. We didn't use it for long though because we realized that our son prefers to have the water poured over him slowly rather than being placed down into the baby tub of water. He's only 4 months old now, but I am certain once he's in the "big bathtub" we will use this again to make sure the temperature is right. Great product!