I ordered 36 of these to replace a number of existing ceiling lights. All bulbs worked out of the box. I have a word of caution for those of you who consider them to be replacements for existing glass (i.e. screwing lightbulbs into the ceiling). You can install them over the round opening of the jar. But then you get a gap, not a flush. You really need to remove the glass and cut a round hole in a square one. These lights are then installed flush with the surface. I hired a man to do this and for 36 lightbulbs it was about 14 hours of work. However, these investments are worthwhile. The exterior is so sleek and modern that it transforms the look of the room.