Autonomous light - does not need to be connected to a power source to function.

You can do with sunlight. An hour of charging in the sun turns the solar panel into about 20 minutes of continuous light. If you let the flashlight fully charge, the three LEDs will last up to 2 hours. In addition, due to their low power consumption, they have a very long lifespan and - similar to a battery - you are unlikely to have to change their years.
You can shine with it even if it cannot be charged with solar cells. This is mechanically possible - by pulling the built-in cable for emergency charging. Just drag it about 60 times and you can shine for 10 minutes.
It has built-in protection against "overcharge", which also contributes to its longer lifespan.