Here is a VINTAGE MERCEDES ELECTRICAL PART THAT IS LABELED "TESTER".  I am unfamiliar with this part or its specific application.  It came from the parts room of an old dealership which had mainly 1960's and 1970's inventory.  It looks to be in good used condition and I am confident that it works as it was used exclusively for testing purposes.  Please check out the photos and email us with questions before bidding.  Professional packaging guaranteed (see our feedback).  Bid with confidence and good luck.

Check out our auctions and other items on eBay in "The Old Car Parts Store" for many similar items.