Specimen certificates are certificates that were archived by printers and the company as perfect examples of the company’s stock issue.  Specimen’s can be identified by their “specimen” stamp, stamped holes spelling “specimen”, or they are often issued with a serial number of a series of zeros.  Often, they are also issued with no serial number at all.  Specimens can also represent a design that was never issued.  All of these attributes make the specimen stock certificate rarer than the issued version of the share.  Many enthusiasts collect specimens as a whole new category of Scripophily.