Change sign faces in seconds. The patented Quick-Change ™ feature, signs easily slide in and out. Uses laminated coroplast sign faces - light weight and durable. ALL PLASTIC – NO RUST, splinters, discoloration, or maintenance. Won’t tear or scratch car seat upholstery. Molded-In handle assures easy portability. Stacking lugs nest into each other when units are stacked which prevents sliding.