K7 Commercial Wall ThermometerRechargeable Battery Included 18650 Infrared Thermometer accurately measures a persons body temperature in as little as one second. A reading is taken as soon as an individuals forehead is detected within 2 4 inches of the thermometers sensor. A green light will indicate that their temperature is within a normal range, and a flashing red light and audible alarm will indicate that the person has a high temperature. The device can operate independently