These infrared sensors are used to monitor temperatures where contact cannot be made with the item being monitored. In racing, they are commonly used to monitor temperatures across the face of a tire, but they can be used for any non-contact measurement. The sensor will measure temperatures from 0-400°F. The IR Temperature sensor has a 4:1 ratio focal point. That means that when the item being monitored is four inches away from the sensor, the focal point will be one inch in diameter. If the sensor is twelve inches away, the focal point will be three inches in diameter.