Standard screw-in lightbulb with 3 color temperature settings to simulate natural daylight, sunset, and campfire lighting throughout your home.  The settings are easily cycled through by turning your light fixture off and back on in under 8 seconds. When you leave the light off for more than 8 seconds, the light will revert to the most recently used setting, when turned back on, as part of our 'memory' function.This revolutionary lighting design allows you to fully equip your home with circadian-friendly light, without compromising style or having tacky looking fixtures, bulbs, or single frequency yellow or red lights.