I had surgery and was told it was important to watch my temperature. I had an old mercury thermometer and this thermometer. The mercury thermometer always read my temperature under 99. This thermometer read my temperature at over a hundred. This caused me to be a little anxious because I really needed a true reading. A higher temperature meant that I could possibly have an infection. Went to the doctor and they took my temperature and it was the same as the mercury thermometer-normal. This thermometer is now in the trash. Never gave me a true reading was always 1 to 2 degrees higher. What a waste of money.