. . The boonie hat was introduced to the United States Armed Forces during the Vietnam War, when U.S. Army Green Berets began wearing them in the field, along. . with Australian and Army of the Republic of Vietnam units. These hats were locally procured; the camo cloth was usually salvaged from other uniform items. . or with the former from a parachute or made up by the tailor. The name is derived from "boonie", the abbreviated form of boondocks (itself originally. . American military slang derived from Tagalog bundok, "mountain", during the Philippine-American War. Made to current U.S. military specs.. . Brass screen vents. . Adjustable chin strap. . Built in internal map pocket. . Loops around crown for adding additional camouflage or to secure small items. .