Porsche 912 front and rear side marker bulbs utilize a 12821 bulb size across both locations. The replacement chart covers vehicle production spanning 1965 to 1976.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche 912 uses the 12821 bulb for both front and rear side markers across all listed model years, spanning 1965-1969 and 1976.
The 12821 is a Philips part number designating a miniature wedge bulb in the T10 form factor.
T10 refers to a tubular bulb with a nominal width of 10 millimeters, a standard sizing classification in automotive lighting.
The 12821 bulb uses a W2.1x9.5d base, which is the wedge-type base standard for T10 bulbs, where the electrical contact is made through the wedge-shaped glass pinch rather than a separate metal base.
The electrical rating of the 12821 is 12 volts and 5 watts, consistent with low-current marker light applications in 12-volt automotive systems.
Because the same bulb size applies to both the front and rear side marker positions on the Porsche 912, a single bulb type serves all four side marker sockets on the vehicle.
The W2.1x9.5d base designation is not universally interchangeable with other wedge base types, as variations in wedge width and pin spacing exist across different automotive bulb families.