Ritow Manifold Slide Rule
Frederick Post model 1465  [1925-1930]

Back has "Table of Constants" which includes "The Frederick Post Company ... MADE IN GERMANY ... Pat'd U.S.A. 1/32/22" 
The 1/31/22 patent was issued to Herman Ritow. 
 
Models 1464, 1465 and 1466 appeared in the 1925, 1927 and 1930 Post Catalogs.  The page shown here is from the 1927 catalog. 

Model 1465 cost $11.40 ($12.45 with leather case) in September 1927.
For more information on Herman Ritow and Post "Ritow" slide rules, click here. 

These slide rules were made by Hoch, Huxhold & Hanneman in Hamburg.

 Rules identifed as "adjustable" use the DRGM 192052 friction adjusting mechanism.