A gold color metal and enamel device 1 1/8 inches (2.86 cm) in height overall consisting of a gold Korean A frame bearing at top a red and blue taeguk and entwined threefold horizontally around the frame a blue scroll inscribed SUSTAIN at the top, SUPPLY in the center, and MAINTAIN in base, in gold letters.
The original units activation and service in South Korea are indicated by the red and blue taeguk from the flag of the Republic of Korea. The Korean A frame with its capability for supporting incredible loads of supplies, also serves as a prop along the way, signifies the direct support mission of the original and current unit and also refers to the motto. The two parts of the taeguk (the yin and the yang symbols) and the upright frame, allude to the numerical designation of the organization.
The distinctive unit insignia was originally approved for the 21st Direct Support Group on 5 June 1969. It was redesignated for the 21st Support Group with the description and symbolism revised on 20 February 1991. The insignia was redesignated for the 21st Support Brigade on 7 November 1997.