10-inch Universal Slide Rule
Frederick Post model 1452 [1936-40 and 1947-50]
Hughes-Owens model 1771
Hemmi model 50

Thin 10-inch Universal Slide Rule
Frederick Post model 1452T [1937-40]
Hemmi model 50F

The 10-inch "Universal Mannheim" was Post's most important closed-body slide rule from 1931 until the end of the slide rule business.  From 1931 to c1950 the top surface was 28 mm wide (the rule discussed here).   After 1950 the rule was 34 mm wide and the model number was "1452W."
1452 (left)     1452T (right)
Edge picture shows both rules 

Top edge: 0-10 inches (Slanted)
Bottom edge: 0-28 cm (Vertical)
Back of slide:[S, L, T]
Back of rule: Table on thin plastic

This page is from the 1936 (18th Edition) Post Catalog 
The term "Universal" is new and seems to be Post's term for its best products.  Hughes Owens used the same termnology. 

Model 1452T first appeared in the 1937 Price List  as a  "New Item": 
"UNIVERSAL SLIDE RULE.  10 inch, like No. 1452 but thin model, in fabricoid case with instructions.  Each  $5.00"   There was also a model 1452TL in sewed leather case for $5.75.