Mercedes-Benz SL550 Map Light Bulb Size

The Mercedes-Benz SL550 map light requires bulb size 12961 or H6W depending on the specific version required for the interior lighting system. Data for the bulb specifications covers the range from 2007 through 2012.

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
2011-2012	12961
2009	12961
2007-2008	H6W

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961
ECE standard (Europe & worldwide). Single-filament signalling bulb with BAX9s base. 12V, 6W.	H6W

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Additional Notes

The Mercedes-Benz SL550 map light specifications reference two distinct bulb types across the model years covered: the 12961 and the H6W.
The 12961 is a Philips part number designation for a miniature wedge bulb built on the T10 form factor, using a W2.1x9.5d base and rated at 12V, 5W.
The H6W follows the ECE standard, which governs bulb classifications used across Europe and internationally. It is a single-filament signalling bulb fitted with a BAX9s base, rated at 12V, 6W.
The W2.1x9.5d base of the 12961 and the BAX9s base of the H6W are physically incompatible with each other. A wedge base and a bayonet-style base require different socket designs, making the two bulbs non-interchangeable.
The SL550 uses the 12961 for the 2009, 2011, and 2012 model years.
The 2007-2008 SL550 uses the H6W for its map light fitment.
The one-watt difference between the H6W at 6W and the 12961 at 5W reflects a minor variation in power draw, though both operate on a standard 12V automotive circuit.
Because the 12961 carries a manufacturer part number rather than a universal ECE designation, sourcing equivalent replacements may require cross-referencing against the T10 W2.1x9.5d specification rather than relying on the Philips number alone.