I AM Black History Yard Sign Letters - Black History Month Yard Cutout, African American Pride, Black History Yard Sign with Metal Stakes. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These Black History Month Yard Letters full color direct printed graphics are vertically fluted for use with a Stakes. Coroplast is typically used for yard, parking, real estate, and election signs. They are waterproof.