This Underground Lighting collection is focused exclusively on the D4S bulb, a mercury-free Xenon HID headlight bulb engineered for OEM projector-based headlamp systems. The D4S Xenon HID bulb is an OEM high-intensity discharge light source that produces illumination through an electric arc inside a xenon-filled arc chamber, rather than a filament or LED emitter.
D4S bulbs are defined by their P32d-5 indexed twist-lock base, integrated igniter, and 42V AC / 35W operating requirement, which differentiates them electrically and mechanically from D2S and D1S bulbs. Although D4S bulbs may appear similar in shape to D2S, they are not interchangeable, as D2S systems operate at 85V AC and use external igniters. Using the wrong ballast - 55W OR 34W or bulb type can prevent ignition or cause permanent component damage.
A core distinction of the D4S HID bulb is its mercury-free construction, making it RoHS-compliant and certified under ECE R99 regulations. This eco-compliant design is mandatory in many newer vehicles and markets, particularly across EU-regulated regions. As a result, D4S bulbs are commonly found in Toyota, Lexus, Subaru, Honda, and Infiniti factory HID systems, where environmental compliance and optical precision are required.
This collection includes:
- D4S Xenon HID Headlight Bulbs (35W) in 6000K white and 8000K white with blue tint
- D4S 5000K Extreme White Xenon HID Bulbs, engineered for higher perceived brightness while maintaining projector-safe beam focus
Typical light output for OEM-spec D4S bulbs ranges from ~3200 to 3500 lumens per bulb, comparable to D2S and D3S formats when installed in matched projector optics. 4300K remains the OEM standard for maximum usable road illumination, while 5000K–6000K offers a cleaner white appearance. Higher Kelvin options such as 8000K shift beam color toward blue, reducing effective lumen output in favor of style.
D4S bulbs are designed exclusively for projector housings, not reflector housings, where the cutoff shield and lens system control glare and beam shape. They are most commonly used as primary low-beam headlights, often within bi-xenon projector systems that use a mechanical shutter to enable high-beam functionality. Correct twist-lock installation, ballast compatibility, and vehicle-specific fitment verification are essential to preserve beam accuracy and on-road legality.
This category supports OEM replacement and aesthetic upgrade paths through Underground Lighting, offering spec-matched D4S bulbs designed to maintain electrical stability, optical performance, and regulatory compliance.
Take a moment to discover our complete HID conversion kits, Replacement bulbs & accessories & wide variety of LEDs - fog lights, turn signal lights, and switchback turn signal lights, and use the bulb finder to ensure the right match for your vehicle.
