Background Trimming (Oval) Description
A green oval background on which are three diagonal stripes from upper left to lower right, black over red over gold (yellow) each stripe 1/8 inch (.32cm) in width; around the oval a 1/8 inch (.32cm) green border, the overall dimensions 2 5/16 inches (5.87cm) in width and 1 7/16 inches (3.65cm) in height.

History
The background trimming was approved on 12 Mar 1970.

Source: The US Army Institute of Heraldry