10-Inch Mannheim Adjustable Slide Rule
Frederick Post model 1449  [1925-1930]
 

This identical page appears in the 1925, 1927 and 1930 Frederick Post Catalogs
In specimen gutter: "FREDERICK POST CO.   MADE IN GERMANY." 

This rule was made by Koch, Huxhold & Hannemann. 

The catalogs say models 1448, 1449 and 1450 have "new rimless indicator" but the related illustration in the catlogs shows a framed indicator.  Most of the specimens I am familiar with have framed indicators but David Cady has a model 1449 specimen with a frameless indicator.   

The catalogs show model 1449 with slanted  top and bottom edges but all the specimens I am aware of have vertical bottom edges.  Post catalogs were frequently wrong about details.