I had one one time (my in-laws thought it was a good gift) carried it around in my pack.
I had a nice bull standing 50 yards down wind of me, and thought I would give him a dose (Cow-in-Heat)....
Pushed the button on the damn thing...

P-P-S-S-S-S-S-S-S-H-H-H-H !

could not get it to stop !

loudest frigging thing I have ever heard as a scent dispersal unit.
Sure got his attention, but not in the way I wanted.....
(but then again, I was not following directions....)
would not buy one....