5-inch "Dual" Duplex Slide Rule
Frederick Post model 1442 [1945]
Same as Roos SR-108

A wartime product.


On Roos-made rules the red ink fades easily and the celluloid facing turns very yellow.

This is a wartime product.  Notice how little metal is used.



 

Excerpt from 1945(?) Price List 
Second price is per dozen