A neck gaiter or neck warmer is a neckwear, or an enlarged collar of a garment, that is worn around the neck for warmth. It is usually a closed tube of fabric, often thick fleece, merino wool, synthetic wicking, or knit material, which is slipped on and off over the head (unlike a scarf, which is an open stretch of fabric wrapped around the neck) to cover the entire neck and conserve body heat. Some balaclavas are essentially a small hood attached to a neck gaiter. Like gaiters for the lower legs, a neck gaiter augments the protection offered by other garments.
Some longer neck gaiters can also be pulled up and cover the lower face as an improvised face veil to help keep out sand/dust, smoke and other airborne irritants from entering the mouth and nose, to prevent cold hives and/or frostbites by wind chills (especially on exposed nosetip), or to protect the facial skin from harmful sunlight during prolonged outdoor activities (e.g. recreational fishing).