Personalized Graduation Yard Sign 2023 - Class of 2023, Grad Sign, Custom Graduation 2023 Yard Sign with Metal H-Stake. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These Custom Class of 2023 Yard Sign for Business 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.