There is no Military Occupational Specialty (MOS) requirement for the Order of the Spur and the order is open to members of foreign militaries serving with U.S. Cavalry units.
History of the Cavalry Stetson
The Cavalry stetson was the headgear typical of cavalrymen during the late 1700s into the 1800s, to include the Indian Wars, Civil War, and Mexican-American War. Before John B. Stetson, for whom the hat is named, introduced the Boss of the Plains hat in 1865, troopers wore hats in a similar style, but quickly adopted the Boss of the Plains as an unofficial standard.
In the modern Army, the Stetson was revived as an unauthorized, unofficial headgear for the sake of esprit de corps in the Air Cavalry. Because they are not authorized by AR 670-1, the regulation for wear and appearance of the uniform, wear and use of the Stetson and the similar spurs is regulated by the unit commander. In most cavalry squadrons, troopers will be authorized to wear Stetsons and spurs on the last day of the work week, at special events, and ceremonies. Like spurs, some units may require a trooper to earn the right to wear a Stetson via a Spur Ride.
While there is no doctrine governing the appearance of a Stetson, it will generally have the wearer's rank set above the unit's regimental crest on the front, with the regimental insignia on the back, and a different color cord around the brim depending on the wearer's branch and MOS. Troopers with combat experience may tie "combat knots" in this cord. The most common cord colors are yellow for an enlisted Soldier, to include 19D Cavalry Scout, black/gold for company and field grade officers, silver/black for warrant officers and chief warrant officers 2 and 3, silver for chief warrant officers 4 and 5 and gold for general officers.
On April Fools' Day, 2011, the U.S. Army released a humorous statement that the official black beret of the Army would be replaced by stetsons. Below is an excerpt from the full announcement:
WASHINGTON, APRIL 1, 2011 -- In a fingertip-to-the-brim nod to its American frontier history, the Army is changing hats again - returning to the tumultuous days of the horse Cavalry in the wild west and adopting a dark blue Stetson as the official headgear for the current force of 1.1 million Soldiers. "We figure the Stetson will be popular with the troops," said Sgt. Maj. Bob S. Stone, Army Uniform Board headgear task force president. "It's been a while since we have changed the headgear, so it's time. Plus a Stetson is functional and down right American." But reminiscent of the controversial switch from the garrison cap to the black beret, the Army faces opposition from one community deeply opposed to losing its special identity with the Stetson - the Armor branch. "Why in the heck are they doing to us what they did to the snake-eaters'" asked one officer familiar with the board's deliberations. "If you ain't Cav, you ain't ought to be wearing a Cav hat. That just ain't right." [...] The Army's official adoption date of the Stetson will be April Fool's Day, 2012.
The statement was supplemented by pictures of soldiers with stetsons photoshopped over their berets, including an Army dog toting a stetson.
- http://www.cavhooah.com A site covering Cavalry history and traditions to include the Cavalry Stetson and the Order of the Spur.