Postcard Mailing & marketing Services The local advertising market is just plain tough small businesses struggle to see value in local advertising. So we built something better. The Choo Choo Confidential is a huge 18"x24' inch high gloss flyer that is delivered to 10,000 mailboxes in a postcard size 9"x12" into your neighbor's mailbox. With no pages to turn or envelopes to open means your ad is viewed, absorbed, and used at your place of business. Ask about our Real Estate flyers custom postcard design, printing, and mailing.