Product review (3 stars): Have slept with better...
Purchased this for arthritic knees - as an aid to more comfortable sleep with this between knees.  Works pretty well, but I have found it to be heavier than expected.  I also tried sleeping with my head on it, but for me that was not comfortable at all as it is thin and cannot be folded or squished to conform to my neck.  So, back to the knees it goes, at least for part of the night until it's too heavy to be comfortable.