BMW / M-B Owners: Because of the way the original halogen bulb clips into the housing, a LED bulb won't be a direct swap without these adapters. These: Specially designed adapters are just for Morimoto 2Stroke 3.0 H7 bulbs. The diameter of the center opening is properly sized just for the 2Stroke H7 base. Recommended: Check your headlights for a similar looking plastic part socket behind the bulb to identify whether or not you need these. All housings would take H7 bulbs and use projectors. By Design: Slotted design allows the wiring for the bulb to slide in from the side, and then original clip assembly will hold bulb firmly in place just like stock.