Top edge: 0-10 inches (slant)
Bottom edge: 0-25 cm (slant)
Back: USBS Circular 47 plus a table of decimal equivalents
On Roos-made rules the red ink fades easily and the celluloid facing turns very yellow.
Excerpt from 1945(?) Price List
|Identified as model "1452D" in both 1944 and 1945(?) Price Lists and on specimens. Specimens marked just "1452" are not known.|