A disc 2 1/2 inches (6.35cm) in diameter overall consisting of three vertical stripes of equal width of blue, yellow and scarlet, the blue to the left, all within a 1/8 inch (.32cm) Army green border.
The shoulder sleeve insignia was formerly that of the Replacement and School Command, World War II, which was charged with the responsibility of training Army personnel. The three stripes are in the colors of, and refer to, the basic combat arms; they also refer to the components of the "One Army" concept: Active Army, Army Reserve and Army National Guard.
The shoulder sleeve insignia was originally approved for the Replacement and School Command on 22 Mar 1943. It was reassigned to the U.S. Army Training and Doctrine Command on 1 Jul 1973. (TIOH Drawing Number A-1-558)