Pillows are one of those things that are very personal. Different types are more or less suitable for each different sleeping position but beyond these “needs” … the “feel” of a pillow can be even more important than a mattress because we sleep so close to it and it seems that each person has a pillow style that they particularly like.
If you mean the “mypillow” you can read a little bit more about how it’s made and what is in it in post #20 here.