During World War II, Felsenthal produced over 75% of the plastic calculating
instruments used by the Army Air Forces, and over 90% of those used by the Navy Bureau of Aeronautics. In the post-war period, it introduced a variety of
plastic items for commercial and technical purposes. This firm was located in
Chicago. It was known as G. Felsenthal & Sons in the 1940s, G. Felsenthal
& Sons, Inc. in the 1950s, Felsenthal Plastics Inc. in 1971, and Felsenthal
Instrument Co. in 1972.
Ref: G. Felsenthal & Sons, Felsenthal Plastics (n.p., n.d.).