Notes: "The K&E 4083-3 (10 inch) and 4083-5 (20 inch) slide rules were formally called the Log Log Duplex Vector slide rules by K&E. The 4083 was based on the earlier 4093 Log Log Vector slide rule. Both slide rules have special scales for hyperbolic functions, and both were designed by Professor Mendell Penco Weinbach of the University of Missouri. The hyperbolic scales on these slide rules were a major innovation and time saver for electrical engineers. K&E made the 4083 from 1939 until 1972. "