The Mercedes-Benz SLK350 parking light utilizes 12961, 3357NA, and 3457NA bulb sizes for the lighting components. Available information for the specified vehicle covers the range from 2005 through 2011.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz SLK350 front parking light uses the 12961 bulb across the 2005-2016 model years in one of the listed fitment groups, making it the most consistently specified bulb in these specifications.
The 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W.
The T10 form factor is a small single-filament wedge type commonly used in low-intensity applications such as parking lights, side markers, and interior illumination.
A second fitment group covering the 2007-2011 model years also specifies the 12961, while the 2005 and 2006 entries in that same group call for different bulb sizes, indicating that two separate fitment configurations existed during the overlapping years.
The 3357NA is an ANSI-standard single-filament T25 wedge bulb with natural amber glass, rated at 12V and 27W, specified for the 2006 model year in the second fitment group.
The 3457NA is an ANSI-standard dual-filament T25 wedge bulb with natural amber glass, rated at 12V with a 27W main filament and a 7W secondary filament, specified for the 2005 model year in the second fitment group.
The 3357NA and 3457NA share the same T25 wedge form and natural amber glass construction but differ in filament count, which affects their function and interchangeability. Substituting one for the other is not supported by these specifications.
Natural amber glass, as used in the 3357NA and 3457NA, produces an amber-colored output without a separate lens or coating, a construction method recognized under ANSI and SAE standards for turn and parking light applications.
The W2.1x9.5d base of the 12961 is a metric wedge base designation and is not physically compatible with the T25 wedge base used by the 3357NA and 3457NA, meaning these bulb types are not interchangeable despite all being wedge-style designs.
The wattage difference between the 12961 at 5W and the 3357NA or 3457NA at 27W reflects a significant difference in light output and socket load, which is relevant to socket and circuit compatibility.