Unlike the test leads that come with most portable, pocket size multimeters, the benchtop multimeter's test probe I had has a "cap" that sits tightly on and covers the banana plug. I'm thinking it would be a nice idea to also mount these caps on the banana sockets on my benchtop multimeter's and not to leave them all exposed to humidity or dust. I also wonder why only the probe has a cap on, but not for the female sockets on the obviously more expensive multimeter itself.
But what are they called? I've tried searching for banana jack shield, banana socket cover, banana connector cap and all sorts of possible mix of keywords I can think of but nothing turns out remotely close to what shown in the picture.