The water activated/manual unit is a state-of-the-art rescue light that uses a microprocessor to combine all the recommended features of a rescue light into one product. When you hit the water, the light will automatically turn on into astrobing mode to attract rescue. When rescue is close, you press the switch and it goes into a steady light to direct rescue towards you. After rescue, you press the switch one more time to turn it off. The light will reset back to water-activated mode.