A rectangular, even pillow differs from the usual one only by the filler. This pillow is not designed for any particular sleeping position, it can be rotated and flipped to either side. It will be comfortable to lie on it in any position.
This pillow is specially designed for sleeping on your side. In this position, it is difficult to get comfortable, because the head is high above the level of the bed. This pillow will allow you to comfortably arrange your shoulder in the recess, and so comfortably and correctly positioning your head.
This pillow will support you in the supine position and keep your head upright if you turn it around. Thus, you will avoid pressure on the skin of the face during sleep. It is also a good choice for beauty treatments.
This form is the most popular and well known. It supports the natural curves of the neck and relaxes the muscles, keeping the head in the correct position.