Plotting Board Mark 7 MIL-B-5046B

This is an authentic US Navy pilot's Chart Plotting Knee Board Mark-7 (MIL-B-5046B), likely 1950's to Vietnam War era. 

Likely designed for a jet aircraft (note fuel is measured in lbs), this 9.5 x 7 x 1 inch device included the flight computer on the face with a rotating card for determining the critical factors impacting the planned flight. By depressing a button in the lower right corner, the top flips open to reveal a map compartment, clips for two pencils, a navigational ruler, a scratch pad, and a battery compartment used to power a lamp to illuminate the maps and backlight the flight computer.  Affixed to the bottom is a knee strap with buckle.

It is in reasonable condition given its age.