Constructed from olive wool, the tunic is outfitted with a set of brass Air Service buttons on the sides of the standing collar, with an embroidered air service patch on the right sleeve, one gold ribbon overseas service (6 months abroad) and a red-on-green private's chevron on the left sleeve. The left shoulder features an embroidered patch, a prominent black block "A" on green background, with a skeleton wielding a scythe in the top and an American aviation roundel with a blue "13" in the center at the bottom. The large "A" is a traditional symbol of the First U.S. Army, a core unit of the WWI American Expeditionary Forces and one of America's longest standing field armies. The 13th Aero Squadron, also known as the "Grim Reapers" for the use of the scythe-wielding skeleton mascot "Grim Oscar" on their aircraft, was a daylight pursuit squadron and a component of the 2nd Pursuit Group of the First Army. Seeing action at the St. Mihiel Offensive and Meuse-Argonne Campaign, the 13th produced a number of aces, including then-Major Carl Spaatz, first chief of staff of the fully formed United States Air Force. The shirt is green wool, with no maker's marks.