This hat is made by ’47 brand. It is a a fitted (Large) franchise model and 100% cotton. I picked it up in Arizona in 2006, right after they changed their color scheme from their original purple, teal and copper look.
A similar hat is still available at Lids.
I wore this hat to a Festival International meeting today.
https://www.lids.com/arizona-diamondbacks-47-mlb-47-franchise-cap/20847427
http://www.festivalinternational.org