Keuffel and Esser Co.
(now defunct)

Log Log Duplex Decitrig Slide Rule No. 4181-1C

Based on the 1947 scale set, which never again changed for this model, the LLDD was the prominent slide rule product for working in technical fields as well as students of Science and Engineering.

Copyright Notice: The contents of these pages is copyright 1998-2001 David & Janet Crate.