When they tap the metal part with their beaks a drop of water comes out.
It stays clean under nearly any circumstances, is highly leak-resistant, and is compatible with deicers in the winter for people who need that.
I live in a warm climate, but I'd had my waterers partially-freeze and...
This is what I use: https://www.amazon.com/RentACoop-Pack-Make-Your-Waterer/dp/B07DVSL74D/ref=sr_1_4?crid=2EACC3WCVK9KG&keywords=horizontal+chicken+nipples&qid=1657892881&s=lawn-garden&sprefix=horizontal+chicken+ni%2Clawngarden%2C1413&sr=1-4
For 23 adults and a mess of juveniles, I have 3 large horizontal nipple waterers with a total of about 14 nipples.
This is more nipples than they really need, I think. 4 on the big bucket instead of 6 would have been enough. But I want another waterer to ensure that they have enough for 2 hot...