Patriotic Happy 4th of July Yard Sign, Coroplast US Flag Stars Stripes American Fourth Of July Independence Day Yard Sign with Metal H-Stake. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These 4th of July God Bless America Patriotic Stars and Stripes American Flag Independence Day Fourth of July Yard Sign full color direct printed graphics are vertically fluted for use with an H-Stake. Coroplast is typically used for yard, parking, real estate, and election signs. They are waterproof.