Purchased in Bulk. These are Sylvania 3157K bulbs. Same thing as the Sylvania 3157LL Long Life. The Long Life bulbs use Krypton Gas and this is where the 3157K gets the K after the bulb #. Sylvania Long Life Miniature Incandescent Lamp comes with increased bulb life to various lighting applications. This lamp has been engineered to withstand sizeable amount of road shock and vibration. It is constructed with a robust filament and proprietary gas mixture that extends performance twice as long as most standard lamp. This lamp is designed to be durable lower maintenance and provide greater safety.