Really loud,  scares the dog :)
926188
I'm sure this would work fine on a larger dog, my pomeranian mix is 13lbs and is scared to death of the sound...runs confused at what I'm doing that for. It is exactly what I would have wanted but the click is a good long ,deep, strong sound that frightens a smaller dog. Who knew? Well constructed and easy to use.
327204
I got this on a whim because my dogs bark at anyone who walks in front of our house.  If the neighbors are going to their cars, they bark. It drives me and my husband nuts.  All I have to do now is go outside and turn this thing on and they stop.  I don't keep it on all day because any noise will set it off and we have chimes hanging nearby.  It can be set for 15-25-50 feet.  One of my dogs isn't as irritated by the noise, but she does quieten down.  Plus, this is so cute, it just looks like a little birdhouse hanging from our porch.  Love it!
1266074
maybe a little too loud for one of my dogs.  got scared of loud pop, but other dog had a blast chasing and fetching balls!
4671244
The second toy I purchased at the Pet Expo 2015 and a growing favorite for my mischievous pooch.

Let me warn you though, this toy is loud and you will find it very annoying after a few seconds but your dog will love it unless he or she hates loud squeaker toys.

This toy is not meant for small dogs or extra large dogs. The toy is pretty big and small dogs might have trouble getting ahold of it while large dogs may just destroy it on the spot. As with any dog toy, I highly suggest you supervise your dog while playing with this toy.

Pros:
Price (great deal when I got it)
Design (easy to throw, grip and find)
Squeaker (my dog loves it and it drive him insane which he likes being)

Cons:
Material (the rubber will not last and don't be surprised if your dog tears it in just a few minutes)
This toy is not really meant for indoors so careful throwing it around, you will break something in your home.
The ridges make it easier to grip but also easier for your dog to tear apart.
Squeaker (I hate it!!!!!)

 Overall my dog loves his new toy and constantly barks for me to get it for him. I personally like that he likes it but I cannot stand the sound of the squeaker. Also the rubber is not durable which means I will need to constantly keep an eye on him or any dog that plays with this toy.
2129900
It is SO loud. I thought it would be at a pitch that only animals could hear, but even people can hear it! Wish I could return it because we won't be using it, but I missed the return date.
4950961
I have two beagles who can be pretty vocal at times, which is a problem since we live in an apartment building with neighbors close by. One dog responds immediately when this comes out. He just has to see it to calm down and will stop making noise. The other dog does not care at all; he continues to bark, squealing each time he gets shocked.

If you have a well behaved dog, he'll probably respond well with this. A stubborn dog won't change his ways just because of a shock or two.
600675
Just to start with a little background.  We have a female lab (10-years old) and a terrier/chihuahua mix (2 years old).

Memorial Day 2010, we adopted a 7-month old female lab from a shelter.  Three months later, she started barking excessively from 11pm-2am.  After 3-days of lack of sleep (sometimes I only get 3-4hours sleep due to her barking), I ordered the NoBark 10R when she would not stop barking (it was around 1:45am when I logged on to amazon.com).  We knew her reason to bark is not justified, because our two other dogs weren't even barking.  We knew it's a legitimate threat when the 10-yr old lab starts to bark.  However, the old lab wasn't barking whenever the little lab would bark.  I think our little lab was starting to mimic the excessive barking of our neighbor's german shepherd (covered in another story).

First night:
I waited for the little lab to bark again.  True enough, it was around 11pm when she started barking again.  (NOTE: our old lab and terrier mix was sound asleep while the little lab was barking.  Hence, no immediate REAL threat in the area).

I gave the little lab a few kibbles to eat while I put on the NoBark 10R.  Based on other reviews here on amazon.com, I set it to Pregressive Correction (#2).  I send her out and her first set of bark was kind of raspy at the end.  I guess she felt the level 0, but not sure what it was.  She attempted to bark again, and this time, she was startled and didn't know what it was.  She kind of jumped and jerked while trying to run away (she wasn't even sure why or whom she was running away from, lol).  It was heartbreaking for a few seconds, but she never attempted to bark again that night.

Our old lab and terrier mix came out of their houses to investigate what could have happened to the little lab.  No one had a slight idea, nice.

The little lab was wearing the NoBark 10R until 6am, never heard a bark all-night.  Second night, I decided not to put the NoBark 10R, I shall wait until she barks again (around 11pm).  11pm, 12midnight came, she wasn't even barking.  She learned quickly when barking is ok, smart lab!

SECOND NIGHT:
She wasn't wearing the NoBark 10R, but still not barking excessively at night.

THIRD NIGHT:
Not wearing NoBark 10R, but still not barking excessively at night.

I have only used the NoBark 10R for one night, and our little lab learned quickly.  She used to bark excessively even on day-time (tolerable since I'm not trying to go to sleep), but she has calmed down since.

This is worth the overnight shipping I had to pay!

Thanks!!!!
879672
It's louder than I thought it would be!!
I originally bought this to see if I can use it to train my APBT but the clicking noise just scared him T^T
I tried muffling it by putting it in a rolled up sock before clicking and it seems to do the trick!
524725
It can scare animals with the noise it makes -maybe.  It has zero zap power.  It could actually make things worse for you.  It is a toy.
2001059
My dog loves this toy! It is her favorite toy to play fetch with in the backyard! (And she's a husky, so playing fetch is not a natural game for her!) I was worried she would try to rip it apart, and she has tried a few times. Luckily, because of the rounded edges on the frog, she has not managed to get a secure enough grip to tear a piece off.  Be warned, the squeak is very loud on this thing. Not the most fun noise to be awoken by at 4 in the morning...silly puppy!
630768
I tried it for the first time last night.  It is very noisy - I gave it to my dog in his crate - to lessen the impact (the crate has blankets).  He was somewhat clueless as to what to do with it - so was I.  If you throw it around enough - and believe me it is not quiet - the treats will come out - i think he is used to his kong - so tries digging the treats out with his paw - which won't work.  Not sure this is for him.  I think I would prefer one made out of rubber .  I wouldn't feel comfortable leaving him alone with it - since in frustration - he might try breaking it with his teeth.
3130785
Just got this.. AMAZING.

When the thing is turned on with no water, it's crazy loud.. i was scared.. until i put water in there and now I can't even hear it.. it's like super quiet..  my dog loves it!  holds a lot of water too..  Im buying another one for my office.

 I give it 5 golden paws!
4856054
There are a lot of squeakers on this snake and each one is really loud so if you have more than one going at a time it can kind of drive you crazy.  It's held up really well and my dogs like to play tug of war with it.  They haven't destroyed it at all which is very uncommon (Australian Shepherd and Border Collie.)  It's just too loud if you have a young baby in the house, which we do.  At least the squeakers are really large so they're not as high-pitched as some toys.

Update: My 9 month old son loves this toy.  It's easy for him to squeak it and it's really fun for him.
2210780
This is such an awesome dog toy however my dog does not like loud noises she's a bit skittish and this thing can be quite loud especially fired indoors which I would not recommend because this thing actually shoots tennis balls at an extremely high velocity my friends and I were playing with my dog in the backyard with this tennis ball  gun and had discussed that being shot with this would not be pleasant at all it's shoots quite fast and far much further than I imagined it would
639770
Terrifying to hear in the middle of the night but my lab and beagle both love it.
3085607
It's driving my dog crazy!!!  He's chewing so much to get to the squeaker. It stopped squeaking after the first day but started again the next. I think it was just full of dog slobber. Lol
777577
As the leash is pulled out, it made a pretty loud sound, the latch is smaller than expected too -which concerns me with our larger dogs but overall, seems to be working well for our dogs, 1 is 60+lbs and the other is 100+lbs.  Just doesn't seem as "Heavy Duty" as listed.