A First Line in our serious tactical equipment a "belt" equipped with the gear we would need fo combat. This would include their main weapon, one or two refills, a knife, a small first aid kit.
If a soldier had to shed its heavy equipment for greater freedom of movement, such as during an escape or escape behind enemy lines the first line ought to serve to survive as long as possible.
We leave you some examples we have found as you can montaros your First Line Kits:
Then you have a video of how to configure your first line: