Not sure it really helps
I read other reviews.  Some said it works wonders, others said it didn't help.  I fall in that second category.  It did have a bad , slightly nauseous chemical smell (from the foam polymer?) when I got it, but it dissipated over two weeks as it aired out of the box.  Not really comfortable, but I got used to it.  I've used it consistently 4-5 times/week for over a month and can't say I feel any improvement.  Feels similar to using a tightly rolled towel as my chiropractor recommended, so I would go that route to try before buying this item.
Rating: 2 stars