Mercedes-Benz C55 AMG front side marker bulb size 12961 and rear side marker bulb size 12821 are specified in this replacement chart. The data covers 2005 to 2006 vehicle production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C55 AMG uses the 12961 bulb for the front side marker position across the 2005-2006 model years.
The rear side marker position on the C55 AMG uses the 12821 bulb across the same 2005-2006 model years.
Both the 12961 and 12821 are Philips part numbers belonging to the T10 miniature wedge bulb family, which is one of the most widely used bulb formats in automotive lighting applications.
The T10 designation refers to the bulb's tubular envelope, a form factor commonly found in low-intensity vehicle lighting positions such as side markers, parking lights, and interior lamps.
Both bulbs share the W2.1x9.5d base type, which is the standardized wedge base used across the T10 format, allowing the bulb to be retained by friction within the socket rather than by a bayonet or screw mechanism.
The electrical rating for both bulbs is 12V at 5W, placing them in the low-wattage category consistent with indicator and marker lighting rather than primary illumination functions.
Although the 12961 and 12821 share the same base type, voltage, and wattage, they carry distinct Philips part numbers, which indicates a manufacturer-level distinction between the two that may relate to filament construction or light output characteristics.
The shared W2.1x9.5d base between the front and rear bulbs does not confirm interchangeability, as the differing part numbers suggest the two positions are specified with separate components.