Thats correct... the SIDE of the cap where the strap goes around the front and over the bill... I threw my cap in the trash years ago. It's probebly from the 1970s or 1980s.
That's why I was asking the size. As soon as I saw the back I knew it wasn't a button. You know, I wore that stupid garrison cap for 4 years and never once looked at one of those little strap keepers. I'll be darned. M nty