In looking though a box of panel meters, I found a surpise, a Dekapot model X537-1.
In looking at past posts, I see some discussion of these. IET Labs still sells the DP-1211 and DP-1311 and has spec sheets posted.
This unit is labeled Voltage Divider, Resisistive, Decade. The DP-1211 and DP-1311 are labeled Kelvin-Varley Voltage Divider.
ESI seemed to have pretty broad range of model numbers and there does not seem to be any pattern to them, i.e. X537-1 vs. DP-1211.
Does anyone have specs beyond what I find for the DP-1211 and DP-1311?
Internally, are these similar or are they different designs for different purposes?