SYLVANIA D4S High Intensity Discharge (HID) Bulb, (Contains 1 Bulb) HID lighting is light from a plasma discharge rather than a filament HID uses less energy than halogen lighting, while producing 3 times more light Light lasts up to 3 times longer than conventional halogen technology OEM (Original Equipment Manufacturer) precision and quality for consistent performance Compatible with existing D4S headlamp optics