A gold color metal and enamel device 1 1/16 inches (2.70 cm) in height overall consisting of a scarlet isosceles triangle point up, charged with a gold sea lion holding in upper paw a gold sword, all in front of a gold masoned triple-towered castle with blue windows rising above the triangle and all in front of a gold outlined white disc with rays enclosed at the sides and base by a triple-arched scarlet scroll terminating below the towers and bearing below two white stars respectively on the left and right, the inscription CONSTRUIR on the left, Y in base, and DEFENDER on the right, all letters gold.
Scarlet and white are the colors used for the Corps of Engineers. The scarlet triangle bearing a gold sea lion, from the seal of the President of the Philippines, denotes the units service in World War II for which it received the Philippine Presidential Unit Citation. The four stars refer to participation in four wars: War with Spain, Philippine Insurrection, World War I, and World War II. The castle with blue windows, suggested by the coat of arms of Manila in the Philippines, indicates campaigns in that area during three of the wars. Additionally, the masoned castle and the sword held by the sea lion allude to the Groups mission and motto which is translated TO BUILD AND TO DEFEND. The gold outlined disc with rays refers to California, The Golden State, and alludes to the Groups allotment to the California Army National Guard.
The distinctive unit insignia was approved on 2 December 1971.