Night Vision devices are designed for use in the dark. It may be harmful and can damage the device if you use it during the daytime or in other very bright situations. Keep in mind that strong direct light, such as projectors, car headlamps, strong flashlights, and so on, may be harmful to your Night Vision unit if you direct your device at the source of these intense lights. With this said, Bushnell Night Vision devices have electronic protection against such damage. Most of these simply turn off overloaded circuits, but some have more sophisticated and separate light sensing mechanisms.