If you sleep on your back, choose a medium firmness pillow so that your head is supported but you have only a very gentle curve through to your back. Our Hotel Collection Luxurious Back Sleeper Pillow is filled right to the edges to provide medium support and deeper sides providing optimal fullness. The box pillow is great if you prefer a fuller pillow; and it fits a standard pillowcase. All our synthetic pillows are non allergenic, which means there's nothing in them that could cause allergic reactions; which is great for peace of mind and essential of allergy sufferers.