Shown one size 7, 1977 dated.
Seems very common and popular among Army Rangers in 1980s, but really hard to find nowadays. Another weird thing, the NSN of the this cap referring nothing in all databases. The only thing I can figure out is the NSN is not completely nothing, I found the NSN of this cap (size 7) is in a continuous sequence of five NSNs in some databases, so I made the NSN-size chart based on other five-sized headwear (like ERDL Hat).
Stock Number Reference:
Cap, Utility, Field, Cotton And Polyester, Poplin, OG-107
Assign Date: (Acquired)