These are HID adapters required for the HID installation on any E39 1996-2000 and Mercedes High Beam on some models. Allows you to mount the HID bulb to your headlight.
E39 was made between 1996-2000 in the USA. Your factory headlight bulbs are mounted in a special adapter. For this reason these HID adapters are required.
BMW X5 2002-2003 - Certain Models may require this adapter for HID installation
Mercedes 2002-2006 W211 High Beam
For this adapter you must either cut and resplice your HID bulb wires (to run the wires through the back hole), or you must drill the hole on the adapter bigger. The manfacture who made these adapters didn't think about how people would run the HID bulb connectors through the back. The hole is smaller than the HID bulb connector.