Megaman Sensor energy saving light bulbs have a built-in light sensor, which automatically switches the light bulb on at dusk and off again at dawn. With a long lifetime, these bulbs are perfectly suited for outdoor security lighting without the expense and hassle of timing switches. You can even use them as nightlights or in hallways, porches and stairwells. Featuring Megaman’s unique Ingenium technology, the sensor bulbs have a 15,000 hour lifetime and a fast start up time of just 1 second.