I have a string of Christmas tree lights that only have about 10 or 15 lights on it. Well, actually, right now it doesn’t have any lights on it. I have used all of the bulbs as replacement lights for other strings. I have never bothered to replace the lights because the battery pack eats up batteries and I end up having to spend more in batteries than the string of lights is worth. But I think I found a solution. They now make solar Christmas tree lights that you can use on wreaths. No more battery packs to fill up each season.