The Mercedes-Benz 300SL brake light utilizes a P21W bulb size for illumination. Data for the specific component covers the range from 1990 through 1993.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz 300SL uses the P21W bulb for its brake lights across the 1990-1993 model years. This bulb follows the ECE standard, which governs lighting equipment regulations in Europe and numerous other markets worldwide.
The P21W is a single-filament bulb, meaning it serves one dedicated function rather than sharing a filament for multiple lighting roles such as combined brake and tail light operation.
The P21W operates at 12 volts and draws 21 watts, which is a typical power rating for stop and signal lighting applications in passenger vehicles of this era.
The P21W uses a BA15s bayonet base. The "s" in BA15s denotes a single-contact base, distinguishing it from the dual-contact BA15d variant and making the two types non-interchangeable despite their similar physical appearance.
The Center High Mount Stop Light on the 300SL uses the 12961 bulb across the same 1990-1993 model years. The 12961 is a Philips part number designation for this bulb.
The 12961 is a T10 miniature wedge bulb, a form factor commonly associated with low-intensity auxiliary lighting positions such as high-mount stop lights, instrument clusters, and courtesy lamps.
The 12961 uses a W2.1x9.5d wedge base, which is retained by friction rather than a locking mechanism, contrasting with the bayonet retention system of the P21W.
The 12961 operates at 12 volts and draws 5 watts, a significantly lower wattage than the P21W used in the primary brake light positions.
The BA15s base of the P21W and the W2.1x9.5d wedge base of the 12961 are physically incompatible with each other, and neither bulb is a substitute for the other in any position on this vehicle.