Cold weather hoods and liners keep workers warm in cold temperatures. They cover the head and neck and leave the face or half of the face exposed. Liners can be worn under hard hats and other equipment. They are made of cotton or polyester. Hoods typically are thicker and are worn alone. They are made of poly fleece, polyester or cotton fleece and are brightly colored to enhance visibility. Some may have pockets that hold warming packs.