7440 and 7443 Bulbs (21W / 5W)

7440 / W3x16d (21 Watt)

Single-filament bulb with a W3x16d base (two contact points). Used for functions that require one brightness, such as turn signals or reverse lights.

7443 / W3x16q (5 Watt / 21 Watt)

Dual-filament bulb with a W3x16q base (four contact points). Designed to support two brightness levels, for example, as daytime running lights (low brightness) and brake lights (high brightness).

The difference in functionality: 7440 is suitable for simple light functions, while 7443 allows for dual functionality in one bulb. Note that a 7443 bulb can fit into a 7440 socket, but it will only work with one brightness. Conversely, a 7440 bulb cannot be used properly in a 7443 socket. By choosing the right bulb, you ensure that the lights function correctly according to the car's specifications.

Technical explanation:

• W: Base Type (Glass base)
• 3: 3 mm width of the contact
• x16: Nominal power rating (16 watts)
• q / d: Quadruple (4) contact points or Double (2) contact points