Made for whatever vehicle that has that one Zerk in the hardest place the engineer could find that you can't get on any other way. The new style grease gun uses rubber hose to do the same thing, so what you've got pre-dates rubber. That could be a find of historical significance.
Pre 1930s.. oil and grease resistant synthetic rubber was not available then. Some grease points on the model A can't be serviced without a flexi connection.
The end fits Alimite fittings with the ears that lock on to the fitting. They were on cars before Zerk fittings were invented. In the teens and twenties.