The Extra Fill Pillows have a more tightly packed filling for added firmness. The additional fibre means that the pillow has considerable resilience and is classed as a firm pillow. A firm pillow with a well-packed filling is important to keep a neutral sleeping position. A neutral sleeping position means that the head, neck and spine are set in a horizontal position. If your posture deviates from a straight line, then it could affect the specified areas. The Extra Fill Pillow helps correct your sleeping position and avoids pain upon waking.