Originally, the featured stamps were only available in the region they represented, save for Colonial National Historical Park, where Eastern-National was headquartered. In 1986 the stamps were printed on thin cardboard, which distorted the passbook due to the combined thickness of the cardboard. Each stamp would be mounted onto its respective page with a lightweight, black, adhesive-backed plastic sleeve. Since 1987, the annual stamp series have been minted on a single sheet of adhesive-backed glossy paper, of a quality similar to that of conventional postage stamps.