Now Hiring Yard Sign 18" x 12" Personalized - Coroplast Visible Text Long-Lasting Custom Now Hiring Sign for Business with Metal H-Stake. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These outdoor 18" x 12" Custom Now Hiring 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.