The Dreambaby Rapid Response Clinical Digital Thermometer is equipped with a state of the art fever alert rapid beep indicator. Made from durable materials, it will last for years and is perfect for the whole family to use. The 'Lo' or 'Hi' indications on the display mean that the temperature cannot be measured because the temperature is outside the temperature range; It is standard practice for the majority of digital thermometers to display a "LO" sign when turning the device on. This means "LOW TEMPERATURE". This is because these types of thermometers are made to measure Body Temperature, so when outside the body, the temperature is usually LOWER. Once placed in one of the methods for body temperature measurement, orally, underarm or rectally, the thermometer will give an accurate reading.Dreambaby Rapid Response Clinical Digital Thermometer