I made this hat for my Grandpa for X-Mas. It was very simple but grueling. Ribbing for 9.5 inches, UGH! Still, it’s going to be a really warm hat due to the double-thickness around the ears, and I won’t have to worry about whether it fits him because it’s super stretchy.
This hat pattern was originally developed for people to make and send to Israeli Soldiers. I’m sure it would work for any soldier, though. You can find out more about it here: