I think that they are these[1]. At least that is the same design; the flared-out base fills the ear and stays in better than most others I've seen. I'm not totally sure on the model; the plant my Dad worked at had huge boxes of the things everywhere, so you'd pick up a couple new pair every day. They survive going through the washing machine, so my mother accumulated coffee cans full of them that were left in pockets over the years.

[1] https://www.honeywellsafety.com/Products/Hearing/Hearing_Pro...