k9king skull subdued thin blue line american flag sticker. 6 x 4 inch reflective police support decal k9king the meaning of the thin blue line flag: the blue represents the officer and the courage they find deep inside when faced with unbelievable odds. the black background was designed as a constant reminder of our fallen brother and sister officers. the flag symbolizes the relationship of law enforcement in the community as the protectors of civilians from criminal elements. it is symbol representing the camaraderie of police officers. honor our men and women of law enforcement with this thin blue line flag sticker.