Mercedes-Benz Sprinter Roof Marker Bulb Size

Additional Notes

• The Mercedes-Benz Sprinter uses the 12821 bulb for its roof marker lights across the 2022-2025 model years.
• The 12821 is a Philips part number designating a miniature wedge bulb in the T10 form factor, which is one of the most widely used bulb types in automotive marker and courtesy lighting applications.
• The T10 bulb operates at 12 volts and draws 5 watts, placing it in the low-wattage category typical of marker and position lighting rather than primary illumination.
• The W2.1x9.5d base type is a wedge-style connector, meaning the bulb is held in place by tension from the socket rather than by a bayonet or screw mechanism.
• The W2.1x9.5d base designation refers to a specific wedge base standard where 2.1 millimeters is the wire contact width and 9.5 millimeters is the base length, which determines physical socket compatibility.
• Because the 12821 uses a standardized T10 wedge base, it shares physical fitment with many other T10-designated bulbs, though wattage and voltage ratings must match the original specification to avoid electrical or thermal issues.