Out of the box, this red dot is automatically solar powered. The red dot intensity also auto adjusts to ambient light. If there is not enough light, such as at night, just press the + or - button to activate battery power. Now it will operate like a regular red dot. You can adjust the intensity by pressing + or - buttons. When it is time to power off the unit, just press both buttons at the same time or simply put it away and it will turn off battery operation after 8 hours. The unit is now automatically in solar powered mode, ready when you need it. You can verify the power mode by covering the solar cell. If the red dot is on, you are in battery mode. If it is off, you are in solar mode.