These are exactly what they say they are...plastic sign holders. They're fine. Just make sure you print your sign on thicker paper because regular copy paper will slip out super easily
These are the standard vertical tabletop holders you see everywhere - at conferences in offices at trade shows in retail stores. Print your own 81/2 x 11 sign and simply slip it between the plexiglass covers. The best thing if you need a number of these is the price. Single holders run from $7-$12 each online. Buy a dozen and pay less than half that. Hard to beat.