Mercedes-Benz S550 Dome Light Bulb Size

The Mercedes-Benz S550 dome light requires a 12961 bulb size for proper installation within the interior overhead lighting housing. Data for the specific component covers the 2007 to 2008 range.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2007-2008	12961

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961

Other Locations

Additional Notes

The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, fitted with a W2.1x9.5d base. It operates at 12 volts and draws 5 watts.
The W2.1x9.5d base is a wedge-type connection, meaning the bulb is held in place by tension from the socket rather than by a separate locking mechanism or bayonet pins.
The Mercedes-Benz S550 uses the 12961 bulb for the dome light across the 2007-2008 model years.
The T10 designation refers to the bulb's tubular envelope, which is 10 millimeters wide. This is one of the most widely used sizes in automotive interior lighting applications.
At 5 watts, the 12961 is a low-output bulb consistent with interior courtesy and dome light functions, where broad illumination intensity is not required.