Another recommendation for the AirZound. I've found it very effective. Stops dogs
almost every time... only had to resort to pepper spray once.
FWIW, I don't fill mine very often - only at the same time I'm topping off my tires anyway. Then again, I don't honk at every little thing, only in a situation where it avoids an accident. I don't generally use it as an angry "gar, I'm mad you messed up" honk (usually.
). I've yet to have to refill before tire refill time. Never had mine leak either, but perhaps that's because I don't futz with it once I've got it mounted, aside from refills. Looks to last a second year so far...