I have this in a 1.0 size pillow. Was told this was my size according to my shirt size and because I’m small framed. But had issues with side sleeping and shoulders hurting. So I went 1 size up to 2.0… and my problems solved. Great pillow. No longer get sore areas on my neck and head… and areas where it gets sore on my head and it feeling like it was falling asleep/numb feeling. Have had TBI in the past and it’s been 4 long years of using many different well known pillow brands with no success. Going a size up so far has solved the issues. Hopefully this pillow lasts for its price.