Vintage World War II US Army Forces Navigational Aids Window_Treatment I have a matching plate

I have a matching plate in my shop

A nice vintage brass desk set

once the USA's largest restaurant chain

Date is unknown

The glasses measure approximately 3 3/4" wide by 1 1/4" deep

Vintage World War II US Army Forces Navigational Aids Window_Treatment I have a matching plateOffered are two World War II navigational aids. The black plastic disk is a Time Distance Computer Type D 4 U. S. Army Air Forces, circa 1943. The disc measures approximately 4 3 8" in diameter with a metal center core. Made in USA by J. B. Carroll Co. Front Scale: True Altitude, Air Temp, Press. Alt. (ETA, Air Speed ) Back Scale: Cal. Air Speed, Air Temp, True A. S. (pressure Altitude, Density Altitude) The white disk is made of a heavy card stock