Printing device part - Printing Font Cartridge - What do we have?

Hello All,
We purchased a box of misc. items at an auction of a long closed videography / Printing business. There were a few of these in the box. We have no idea what they are. They are about 11" long, pretty heavy (metal), with pins of varying height along one side. Also a row of gear teeth along one side. Has graphic symbols that makes us think it was a font selector for some type of printing device., Any ideas what this may be?
Thanks