Confederate battle flag used during the Civil War, which remains offensive to some black Americans because it represents the Confederacy and the era of slavery. The flag has a red background, with two blue stripes in a cross, and 13 white stars inside the stripes. Some have described the Southern Cross as a proud symbol of Southern heritage. The Ku Klux Klan and other racist hate groups have also appropriated it. According to the Southern Poverty Law Center, more than 500 extremist groups use the Southern Cross as one of their symbols.