2 Mode light. First is always on mode and second is sensor mode. On mode : always light on. Auto Mode :Sensor work under the darkness or weak light only. It is highly suggested to attach to the wall, fridge or place parallel to human body. not suggest to put them like under the cabinet, not enough space to sense body. but it it is ok to do so if you can guarantee there are enough space to sense human body The usb on left or right side will strengthen the sensitivity when you attach the magnet