This adapter is not enough to screw end completely in most small screw caps, as they are usually surrounded by a black plastic frame which prevents screwing the adapter bottom and thus prevents contact. On screws 4 to 5 lamps with small pellets prevents screwing and only 1 works in the state. To allow the electrical contact, I had file the edges of the black plastic frame with a Dremel (small hobby drill) and a tip to sand.
