This is a Swiss Army issue cold-weather neck warmer or tube scarf. It's a wool blend with a stretchy knit so it can fit comfortably around any neck or face. It's breathable and insulating so it can be worn over the mouth and nose for protection from frostbite. It comes in blue-green grey color as shown in the images and in new condition.
When flat, the scarf measures 13" x 8".