This photoelectric light control senses light levels and automatically turn lights on at dusk and off at dawn plus you can adjust the light sensitivity setting to your own situation. Stop coming home to a dark house or simulate home occupancy to deter intruders without the seasonal adjustments that timers require. You will also save money and energy since lights are only on when needed. Just screw into the light bulb socket of your lamp, whereupon you screw the light bulb into it which adds about 1 and 1/4 inch to the height of the bulb. If flickering occurs the ring has multiple positions around the circumference of the unit that lets in more light and less light. Try adjusting the ring in increments of 1/4†at a time. If the fixture has a reflective surface, the customer may need to turn the ring to a different side to avoid reflections. Shaded areas on porches, under trees, North side of the house, are all more susceptible to the flickering. Bulb Type The unit was designed for incandescent, but will work with dimmable LEDs LED Bulbs can vary dramatically in quality, performance, and power requirements. If a particular bulb is flickering or not lighting trying a different style or lower wattage could help