What is the difference between 3157NAK and 3157NA?

The primary difference between 3157NAK and 3157NA bulbs lies in their design and intended use. The "K" in 3157NAK indicates that the bulb has a dual-filament design, providing both standard and higher brightness options, typically used for tail lights, brake lights, or turn signals. In contrast, the 3157NA is a standard dual-filament bulb without the additional features that the "K" designation may imply. Always check vehicle compatibility to ensure proper function and safety.