Shimano HB-NX50 is a hub dynamo that generates electricity when the front wheel of a bicycle is rotated, allowing you to power lights and other accessories without the need for batteries. It is compatible with 6 V/2.4 W bulbs for the front light and 6 V/ 0.6 W bulbs for the taillight. The dynamo is easy to install and comes with all the necessary mounting hardware. It is also lightweight and durable, making it a great choice for both recreational and commuting cyclists.