I'm a 60-year-old woman with osteoarthritis in my neck. I sleep on my side.
The "patented interlocking fill"? Imagine breaking up the solid foam of a bargain-basement pillow into irregular 2x2-inch chunks and refilling the original pillow cover. The recommended firmness ("White" for my "My Pillow") is a factor of the ratio of number of foam chunks to finished pillow size. The product as shipped is greatly compressed and lumpy. I "plumped it up" in the dryer, as instructed. It was less compressed but still noticeably lumpy.
After one uncomfortable night's sleep, I detected no difference in body-heat transfer/retention and head/neck between a solid foam pillow and "My Pillow." The foam chunks were still lumpy, causing additional discomfort.
I rejected the replacement offer and returned "My Pillow" for a full refund. I do not recommend this pillow.
Product or Service Mentioned: Mypillow Pillow.
Reason of review: Bad quality.