"GRUMPY" Baseball Cap Type Hat Men's Size Small

Please read all of the description information and examine all of the photos carefully before purchasing! Pre-owned, in great condition -- it didn't fit (I was really bummed!), was never worn. There is no size indicated and there is no adjustment, so we measured a 20" circumference vs my 22" head -- hopefully that will help but it is not anything precise since we don't really know how to establish a hat size. A chart found on the 'net said 20" is Small and 22" Medium, for whatever that is worth. Maybe a big kid?