A gold color metal and enamel device 1 1/4 inches (3.18 cm) in height consisting of two black roundels, circumferences conjoined at the horizontal radius, each charged with a cross botonny divided quarterly brick red and white, overall a larger gold roundel bearing a black horse's head and issuing from the top of the roundel a demi-fleur-de-lis, brick red; surmounting the fleur-de-lis and above the roundels a gold scroll lined with brick red and inscribed "FIDELITY TO ENDEAVOR" in black letters.
The three roundels stand for wheels; they refer to the Group's mission of directing motor transport operations. The colors brick red and gold are for the Transportation Corps. The fleur-de-lis, a symbol of France, where the unit was activated and inactivated during World War II, refers to the organization's war service. The red and white crosses are taken from the arms of Lord Baltimore now used on the flag and seal of the State of Maryland. They refer to the two tours of duty the Group served in Baltimore. The black horse is from the State seal of Pennsylvania. It stands for the unit's home area and the location of its headquarters at Butler, Pennsylvania; it also refers to horse-power and to transportation in general, the original unit designation.
The distinctive unit insignia was originally approved for the 300th Transportation Group on 24 September 1968. It was redesignated effective 17 September 2007, for the 300th Sustainment Brigade with the description and symbolism updated.