The non-contact forehead thermometer is equipped with the latest medical infrared technology with 0-8cm effective measurement distance(5-8cm is more effective). You just need to pressing a button when you using this forehead digital thermometer, then it will provides accurate temperature instantly within 1 second. The easy-to-read LED display provides temperature readings in 3 colored backlist with green, orange or red to quickly identify a fever in the dark. If the temperature is on the normal range(95.9℉-99.1℉/35.5-37.3℃),the LCD will show green. If the temperature is above the normal range (default setting of 99.1℉ / 37.3℃), the fever thermometer will emit a warning sound and the LCD will show yellow or red.