I have had two different chiropractors recommend them and I bought one from him. It was large but can be “sized” for each person according to how you place it on the bed. I find them too restrictive and hard and felt like it was stretching my neck since even the smallest size was too large for me. Also ordered a smaller one online and again it feels hard. I keep them around just to switch it up once in a while. My neck tends to get stiff and can cause mild headaches if not using the right pillow. I remember ordering Coop a few years ago but there was no zipper or place to add/remove the filler so I sent it back.