The Mercedes-Benz R350 parking light requires a bulb size of 12961 for proper installation and function within the lighting assembly. Available data for 12961 covers the range from 2006 through 2010.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz R350 uses the 12961 bulb for the front parking light across the 2006-2012 model years.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor.
T10 refers to a tubular bulb with a width of 10 thirty-seconds of an inch, a standard sizing convention in automotive miniature lighting.
The 12961 bulb uses a W2.1x9.5d base, which is the wedge-type base common to T10 miniature bulbs and relies on direct contact with the socket rather than a separate metal connector.
The bulb operates at 12 volts and 5 watts, consistent with low-current parking light applications in passenger vehicles.
The W2.1x9.5d base designation is standardized under IEC specifications, where 2.1 refers to the wire contact width in millimeters and 9.5 refers to the base length in millimeters.
Because the 12961 is a Philips-branded part number, equivalent bulbs from other manufacturers must share the T10 form factor and W2.1x9.5d base to be physically interchangeable.
The consistent use of a single bulb size across all listed model years of the R350 indicates no mid-cycle change in front parking light socket specification occurred during that production span.