100 Amp Current Shunt made by the Sangamo Electric Company, Springfield Illinois. This Sangamo plant location closed in 1978, over 40 years ago, so this item is at least that old, and likely older. There are no marks on the screw terminals and the large solder lugs on each end are perfectly clean, so these are probably unused. Mounted on an 8.25" x 4.0" x 1.0" stained wood block, these are in clean condition for their age.