The Mercedes-Benz GL550 parking light requires a bulb size of 12961 for proper installation and function. Data for the specified lighting component covers the range from 2008 to 2012.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz GL550 uses the 12961 bulb for the front parking light across the 2008-2012 model years.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor with a W2.1x9.5d base.
The T10 designation refers to a tubular bulb with a wedge-style base, commonly used in low-intensity automotive lighting positions such as parking lights and side markers.
The W2.1x9.5d base specification describes the wedge base width and pin spacing, which determines physical fitment into the socket.
The 12961 operates at 12 volts and 5 watts, consistent with the low power draw typical of parking light applications.
Because the W2.1x9.5d base is a standardized wedge format, other T10 bulbs sharing that base type are generally interchangeable at the socket level, though wattage and voltage ratings should match the original specification to avoid electrical or thermal issues.