A gold color metal and enamel device 1 3/16 inches (3.02 cm) in height overall consisting of a gold Philippine sun bearing a red arrowhead all between six fleurs-de-lis forming a "V" with two conjoined to the base of the sun and two to the side, all enclosed by a continuous red scroll beginning in reverse in a convex arc from behind the top of the sun and the two upper fleurs-de-lis, and extending downwardly, inwardly and horizontally and inscribed on the left with the word "SUPPORT," in base with the word "STRENGTH" and on the right with the word "SUCCESS," all in gold letters; the area between the scroll and the Philippine sun all blue.
The enarched portion of the scroll simulates the arc of a rainbow and alludes to the organization's descent from the 1st Battalion Engineers, California Army National Guard. The fleurs-de-lis represent France and the six campaign honors for Lorraine, Champagne, Champagne-Marne, Aisne-Marne, St. Mihiel and Meuse-Argonne awarded the unit for service during World War I. The Philippine sun refers to the organization's Pacific campaigns of the Bismarck Archipelago, Luzon and the Southern Philippines, and with the arrowhead, it also relates to the Philippine Presidential Unit Citation awarded the unit during World War II.
The distinctive unit insignia was originally approved for the 115th General Support Group on 20 September 1968. It was redesignated for the 115th Support Group on 9 December 1975.