LittleLaughing

Hi there, I was going through my dad's things and found two items that I'm honestly not sure what they are. I am guessing they are antique car battery testers given the gauges, but that is only a guess. Do any of you out there actually know what these are? Thanks in advance!

Good evening, I was going through some of my father's items and found a few things that I don't know much about and was wondering if they are worth keeping and would be of interest to anyone.... Parts List for an Essex Super-Six The Challenger book, dated March 1929 (great condition) Instruction Book for an Essex Super-Six, dated January 1929 (also great condition) I have attached a photo of them, but the lighting is off and they are really one color... Thanks in advance for any insight you can provide.