5-inch Mannheim Adjustable Slide Rule
Frederick Post model 1448  [1936-37]
Hemmi model 52
Appears in 1936 Catalog and 1937 Price List

 Dimensions 125 (scale length) x 27 x 9 mm. 

This page is from the 1936 (18th Edition) Post Catalog.  The term "adjustable" is carried over from the previous catalog in error; Hemmi rules did not have a friction adjusting mechanism other than the usual bend-able metal backing plate.