USAF Air Navigation Circular Slide Rule Attack Computer Type CPU-73A/P

USAF Air Navigation Attack Computer Type CPU-73A/P
NSN 6605-00
Made by Felsenthal Instruments Co. - USA
Complete with Technical Manual and heavy duty plastic storage wallet.
This circular slide rule device is 9 inches (23cms) in diameter and made of a plastic composition and is in perfect condition. When in use, I believe that this calculator enabled a Weapons Director to calculate the course required for a fighter pilot to intercept a moving target.
Complete with a 20 page technical manual - no tears, ripped or missing pages , published 30 March 1972 and updated 15 August1977. .