Insert for 16 inch Round Pillow: Lovesoft

I really like this pillow insert. It’s cushy enough to relax with, and provides good support if I’m laying down. I would suggest an 18 inch cover - all the 16 inch covers I’ve purchased and had made are too small and make the pillow too tight.

I bought what is listed on the website as a "16 inch round." The tag on the item itself says "17 inch round." My tape measure says it's 20 inches across.