The device(s) in the pictures are voltmeters. The one that's lit up is a device that is only capable of measuring DC voltage like batteries, due to the options installed within it.
These devices are in storage for the most part, they're too energy inefficient to be used unless there is a need for them. I have a need for the device, so I get it out of storage and take it partially apart. The circuit card connectors all need cleaned and reseated, and it generally needs to be checked out and verify that it still works. In this case, the device is 60 years old and is getting to the point where it's difficult to keep operational. I'll probably have to retire it at some point soon in favor of something else a little more modern.
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