A gold color metal and enamel device 1 1/8 inches (2.86cm) in height consisting of a black disc surmounted by a stylized gold mill-rind with a square scarlet collar and a gold hexagonal socket, interlaced by a scarlet garter with a gold buckle at tope inscribed, "COMMITMENT TO SERVICE" in gold.
Buff/gold and scarlet are the colors traditionally used by Support units. The mill-rind symbolizes support. The unit's numerical denomination "646", is symbolized by the construction if the mill-rind, which has six extensions, a collar of four sides and a hexagonal socket (six sides) at center. Black refers to solidarity and strength of purpose; scarlet denotes courage and sacrifice; gold signifies excellence. The circular garter alludes to the unit's all-encompassing mission and recalls the wheel of the Quartermaster insignia of branch.
The distinctive unit insignia was approved on 29 Feb 2000.