K&E 68 1550 (4168) --- 5" Plastic Duplex Slide Rule
From the collection of Clark McCoy
This rule is unusal in that it came as a boxed set. The instruction manual with it is a late version that is generic for all slide rules copyrighted in 1973. Notice that there is no model number on the rule, just the word "Doric".
Front side with case
Front cover of manual
Copyright page of manual