VS-17 is something that soldiers use to help them be seen by their friends and not their enemies. It's really important to be able to tell who's on your side and who's not when you're fighting in a war.
VS-17 is a square flag that's really bright and colorful. It's usually orange on one side and pink on the other. When soldiers are walking around, they carry it with them or attach it to their clothes or backpacks so that their friends can always spot them.
The reason VS-17 is so bright is that it's made out of special reflective material that shines really well in the dark. So if someone is lost or separated from their group, they can use VS-17 to signal for help and their friends will be able to see them from far away.
Using VS-17 is really important for keeping everyone safe in a war, especially when it's hard to see who's who. By making sure that soldiers can always tell who their friends are, they can stick together and make sure that everyone makes it home safely.