Helloooo...there:

The Archaeological Institute of America, San Diego, still has the
Centimeter Scales available.  They are used by archaeologists, museum
folks and many others to indicate object size in photographs.
Information at  http://www.theglyph.com/scales.html   These are the
standard plastic centimeter scales that were originally produced by the
Government Printing Office for the National Park Service.  Now available
only from the AIA San Diego Society.

Ron Fellows