Great against dogs barking at you.
598280
Worked beautifully for me.  The neighbor's dogs used to bark nonstop at me while I was tending my vegetables along the fence.  I used this device a couple of times: they stopped immediately when they "heard" it, went away and barked from a distance once or twice (just for show).  After that, all I had to do was show them the device; they learned fast.

In the past few weeks, however, they have started barking around 4 am; that wakes me up.  I  am shopping (at 4:30 am) for a stationary device that will shut them up even when I am not facing them.
443498
This product works great and has kept my dog, a Blue Heeler, from driving us insane with his persistent barking. If you have a dog that drives you or your neighbors crazy by non-stop barking, this is the collar for you! This retains the charge for a long time, we do not have to recharge it near as often as I thought we would have to.
3482080
Works pretty well. We have 2 one for each dog and our bigger dog has thicker skin so it doesn't shock every time. But did bring down the barking.
1885832
After 3 weeks of use, I can say that for my situation this is a really great product.  However, I don't think it's a good cure-all for every barking situation.

My problem was a nuisance barker.  One of my dogs (I have 3) would yip for literally hours on end when he was bored, wanted to come in, or just wanted attention.  The other dogs don't do this.  I crate my dogs at night (in the basement), and he would sometimes start yipping in the middle of the night and go on for hours.  I've mounted the Bark-Free near the crates, and it took about 3 yips to cure him.  It was like magic.

I would really hesitate to use this device on other kinds of barking however.  My dogs (Schipperkes) are bred as watchdogs, so giving alarm barks when something in their surroundings says "warn your humans about this!" is hard-wired into them from years of selective breeding.  It's their job, and somewhere in their little doggy minds they get some real satisfaction from doing their job and having it recognized and appreciated.

So I wouldn't mount the Bark-Free by the front door, for instance, to deter barking when someone rings the bell.  I think it's better to let them give the alarm bark, tell them they're good dogs, and then tell them that everything's OK and they can be quiet.  I also suspect that for this kind of purposeful barking, the Bark-Free would likely not be very effective.  The desire of the dog to do its job would overcome its aversion to the ear-splitting sound from the Bark-Free.

But...for the nuisance "I'm bored, wake up, give me some attention, etc." bark, the Bark-Free is the best solution I've found.  I bought it at Sharper Image, and they have a 60-day no-questions-asked return policy.  But I'm keeping it...it works great for me.
393641
We bought this about a month ago and it silenced our dog immediately.  He is quite anxious and dominant so he sits by the window and barks at people walking by.  This device silenced him after about the second or third time he set it off.  Very good product.
1293062
I adopted a dog and my neighbors compalined because he was barking all day. This SERIOUSLY helped. Also used the thundershirt
3763480
I was skeptical that this would be that effective, but it's turned out to be very good. We've had this for a while now, and have had no issues. The actual unit is somewhat big on our 10# MaltiPoo, but we've found it to be a deterrent against barking when we don't want him to. In fact, I don't believe he's gotten the shock, as if he barks and the collar beeps, he stops.
137042
My dogs immediately quiet down with this. Actually know just showing them the can has them lay down and behave. They are great pyrenees so prone to barking at a frog darting 2 miles away haha . It helps with their non stop barking when nothing is around.
629535
I use this to help correct a bad barking habit one of my dogs has developed.  It is a great training aid, as long as you use verbal commands first, then the audible beep, then the vibrate, and last resort...shock.  I like the adjustable shock level.  This collar works well.  The only reason I don't give it 4 stars is because if you need to correct both dogs at once, you have to switch over to the 2-dog setting by pressing the torch button, then the dog button to switch.  Usually by the time you do that, the barking is done and it's too late to correct the dog, as you want to correct them in the middle of the bad behavior.  It would be nice to have a button that just activates both dog collars at the same time.  The auto bark feature seems to initiate when the dog shakes its head too..which is not good, so I leave it off.  Other than that, these are good quality and seem to be working well after about 6 weeks of use.
1389459
This product is excellent. We live in a neighborhood of barking dogs. I pull out the whistle and blow for a few minutes until they are all silent.
222856
I bought this to hopefully prevent my dogs from running the fence and barking at the neighbors dogs. As soon as I hung it up the results were instant.  I can't see through it enough to tell what's on the other side. The dogs stopped barking already. I am very satisfied with this product.
2313077
Works great for our boxer pitbull mix. She would bark at trees blowing in the wind, and birds flying around. Not anymore.
3648085
Dog is funny now.  She gets one bark off and the device does the vibrate thing.  She knows whats coming if she keeps it up.  This is being used with a Blue Heeler.  She can be a little stubborn and has a chilling shrieking bark sometimes.  We were getting complaints from the neighbors.  No more complaints.  Easy to use, battery is lasting long time on initial charge.  Delayed on this for way too long before purchasing.
1372430
Love the product. I use it to stop my dogs from barking when needed. It has a wide shooting range. Highly recommended.
743512
This really works! I was doubtful as it's basically a can of compressed air. But I've only had to use it a few times and already have noticed the dogs aren't barking as much. I have a little Chihuahua mix that barks as leaves blowing by or the sound of the wind, then he would get my two labs going. With all three barking the sound was deafening and almost impossible to get them to stop. At the first growl I used this and they all stopped immediately. Now I just hold up the can and they don't even start barking.
1911554
I used this product to help train my dogs from barking at the tv every time an animal was on.  They thought the animals were real and would bark at the tv.  This product and 'No Bark' command has helped curb that behavior.  I may need to purchase one more time as I am almost out and I'm now trying to train them to not bark at the neighbors dogs when I am walking them.  Overall I think this product works well with consistent training.
172225
This works great for correcting my dog, who barks at everything from our fence. She hates getting wet, so just the sound of it stops her dead in her tracks. The water shoots far, but not hard, so it's not hurting her.