On a nine-pointed star, one point up, 2 3/8 inches (6.03 cm) in diameter and pierced by a one inch (2.54 cm) circle, a red projectile 1 3/4 inches (4.45 cm) in height and 3/8 inch (.95 cm) wide, point up, all on a circular olive drab background 2 5/8 inches (6.67 cm) in diameter.
The design was arbitrarily selected, using the colors associated with the Coast Artillery.
The shoulder sleeve insignia was originally approved for the 9th Coast Artillery District on 12 July 1941. It was redesignated for the Pacific Coastal Frontier on 25 March 1942.