The Volkswagen Cabriolet brake light utilizes a P21W bulb size for illumination across all listed vehicle applications. Available information covers a production span from 1985 through 1993.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Volkswagen Cabriolet uses the P21W bulb for its brake lights across the full 1985-1993 model year range.
The P21W is an ECE-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, a base type that accepts the bulb through a push-and-twist motion.
The BA15s designation indicates a single-contact bayonet base with a 15mm collar, which distinguishes it from the dual-contact BA15d variant used in twin-filament applications such as combined stop and tail functions.
Because the P21W carries a single filament, it is dedicated solely to the brake light function rather than serving a combined role.
The Center High Mount Stop Light on the Volkswagen Cabriolet uses the 12961 bulb across the same 1985-1993 model year range.
The 12961 is a Philips part number designating a T10 miniature wedge bulb rated at 12V and 5W, fitted with a W2.1x9.5d wedge base.
The W2.1x9.5d base is a plastic wedge-type fitting that requires no separate socket hardware, as the bulb's own base contacts the housing directly.
At 5W, the 12961 operates at significantly lower wattage than the P21W, reflecting its role in a smaller, supplemental stop light rather than a primary brake lamp assembly.
The P21W and 12961 use entirely different base types, a bayonet and a wedge respectively, making the two bulbs non-interchangeable with each other.
The T10 wedge form factor of the 12961 is a widely used miniature bulb size, though fitment in any given housing depends on the specific socket configuration of that vehicle.