What is one characteristic of non-pyrotechnic VDS?

Non-pyrotechnic visual distress signals (VDS) are designed to be safe and effective without the use of combustible materials. As such, one key characteristic is that they are non-combustible, meaning they do not produce flames or explosions when activated. This makes them particularly advantageous in situations where a more controlled signal is necessary, as they eliminate the dangers associated with fire hazards.

The other options do not accurately represent the nature of non-pyrotechnic VDS. For instance, these signals do not create flames, making the first option incorrect. They are also designed to be effective both during the day and at night, contrary to the third option. Lastly, while non-pyrotechnic VDS can be used by commercial vessels, they are also available to recreational boaters, which does not limit their usage exclusively to commercial applications.