Covid Testing Available Here 2022 Yard Sign - Coroplast Visible Text Long-Lasting Covid Testing Available Here Yard Sign with Metal H-Stake. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These Covid Testing 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.