Vintage K-4 Automatic Computing Gun Sight For Lower Turret 1940 ca. WWII, NCR

Description

Offered is a Vintage K-4 Automatic Computing Gun Sight For Lower Turret 1940 ca.  This World War II piece of militarily was made by The National Register Company (NCR).  This Gun Sight retains it's original metal tag that reads "Automatic Computing Sight For Turret (Lower Ball), Type K-4, Part 645418, SER. 410348, Cont. W-33-038-AC-409, The NCR Company, Under License From Sperry Gyroscope Company Inc."  The K-3 airborne computing gun sight was installed aboard planes such as the B-17. It aimed the machine gun based on its own motion and the range to the target.  I'm not an expert in Military equipment, but it appears a lens and a knob is missing from this sight.  This piece measures about 13" 10" x 13".  I don't know the functionality or completeness of this piece, so I am selling it "as is."  The dark spots on the pictures are not oil or any other stains.  I washed the piece quickly with water and those are the spots the water didn't dry yet.  A nice vintage military piece to add to your collection.