I'm a side sleeper replacing my several year old IsoCool foam pillow. Already tried another IsoCool however the new version is much lighter and less supportive than my older one and no longer satisfactory. My brother has a Pillow Guy side sleeping model and loves it so I went with his recommendation.
If I didn't know better I would say it was down filled. Construction and cover are high quality.  Unfortunately it's just too soft for me. The fill is not sufficient enough to keep my head in a neutral position when on my side.