One of the more useful and used items I always carry is the bandana. I'm not talking about a little hankie but a full sized manly-man bandana. I usually wear it around my neck for easy access.

I "borrowed" mine from a Navy med kit on a Troop Carrier many years ago and still use it today. It's a triagular OD green piece of cotton and measures something like 3 1/2 to 4 foot long and maybe 3 feet wide.

I've used it from it's intended purpose as a arm sling, to cleaning my weapon, sweat band, head cover (or Do-Rag), dust mask, wash cloth, towel, and even a belt.