This simulator produces a random varying change in output intensity for either a single LED, or 2 series-wired LEDs. The effect realistically mimics the crackling fire in a fireplace or of a campfire. Perfect to add the reflective effect inside a building or house for the added warmth and that "lived-in" look. If used with Ngineering Nano LEDs even the smallest scale scene can enjoy the realism this effect produces, such as an outdoor BBQ or a backyard burn pile.