Okay these collars are AMAZING. They beep at increasing levels, but not to a level that makes your ears bleed, and they vibrate once they hit the highest beep level, which is much much much better than the "gentle static shocks" of other collars, which is just a nice way to say it electrocutes your dog, but on a lower level.
I have a 130lb St Bernard Pyrenese and 90lb Golden Pit, and they bark like mad, but these collars work so well that it's gotten to a point where they don't even need to wear them; I just beep it when they bark and they stop.
Bravo to a safe, kind, and excellent products that works without the cruelty!