The lamps are powered by 4 AA batteries and switch on automatically when switching nearby.The duration spark about 30 seconds is sufficient to move up or down the stairs. To conserve battery power, the lamps do not light during the day or when a main light is on: well done.
The light is very white, but as it is directed downwards, it does not hurt the eyes.
It is a discreet and efficient device, I recommend.