I spent literal hours searching online for a sacral/coccyx wedge after my physical therapist recommended one to help correct posture due to scoliosis. I even bought another product before I found the tush cush and sent it back because the foam was so soft it was a total waste. When I found the tush cush, I measured my tush and found that the car cush would be wide enough for me both at my desk and in the car. Ordered the extra firm because of my previous experience. Received it today and I can already tell it's great. Almost exactly like the one from my PT's office. Good quality, firm, corrects posture while sitting. Yay!