Well worth the money!
I purchased this on 05/28/08 as a last resort for an out of control German Shepherd/collie mix. She was constantly bitting (in a playful manner, but at 72 pounds, it doesnt feel playful), jumping, chasing animals/cars/people, running into the middle of the street, and barking nonstop! I am happy to say that after the first few uses (it took her a couple times to associate the noise/shock with bad behavior, she is now very sweet and very well behaved. For about the past 2 weeks we have even been able to take her into the yard and area around the house without a leash. She stops when told to stop, for the most part, and when she doesnt all that is typically needed is just to show her the remote and she will stop. Very happy with this purchase! I did give it a 4 because the buttons do stick if you are not careful. It is VERY important to watch and make sure the red light goes out on the remote and does not continue to shock her.

gentle and effective
great!
was afraid to zap the personality out of our puppy (OK, he's 14 months now), but it's helped up trim the bad behavior. Zapped him exactly twice, then he learned the tone, then our voices saying "no" sternly. Works like a charm, wish I could use it on my Sophomore English students... but that's another review.
NOTE: don't use produce on people, as much as you may want to.

Seems to work, but its a small sample
My dog is a strong willed Border Collie. The first time it was used, the dog yipped and ignored it, but soon got the message. I haven't had to shock her since and the tone is all it takes. The batteries seem to last well and the construction is reasonable. With the large dog size, there's enough collar material for a very large dog, or a horse. I would rate it 5 stars, but this is one of those things where "your mileage may vary."

THIS WORKS!!!
We tried this in order to train our 5 month old pup. We had a problem with digging in yard, pulling plants and flowers out of ground and other usual typical puppy antics. What we have found is that if she gets zapped once while doing something she should not be doing, she doesn't do it again.We use the audible sound as a warning and that is usually enough and the electronic shock is not necessary. In my opinion, you only want to use the shock for truly unacceptable behavior. Over use to my mind could take the spirit out of dog.

Also, would like to compliment the manufacture for having first rate telephone customer service.....open on a Saturday, the rep spoke knowledgeably and best of all spoke clear english.

AMAZING!!!!!!!!!!!!!!!!!
This collar is absolutly amazing!!! We adopted a 10 month old lab mix from a rescue, although he was very sweet he had NO MANNERS! Never listened, basically did exactly what he wanted to do when he wanted to do it. I reluctantly ordered this collar in hopes of a miracle and guess what? It really was a miracle! In a matter of a week I had a brand new dog! He is very well behaved! He no longer jumps on anyone, he doesn't steal food from the kid's little table, he no longer tries to take food from my kids, he doesn't chase my little chickens, he is the best trained dog I have ever owned!!!! I have to give all the credit to this collar, it changed a dog that I didn't think I could keep into a beloved family member!!!!!!! Also I have to tell you that I only had to use the shock portion of the collar a few times, after that the noise was enough. Do yourself a favor and invest in one of these collars! Just make sure you order extra batteries, and so you know, whatch the battery selection that comes up when ordering because they are not necessarily the right batteries, I order the wrong ones, and I ordered them with the collar, so be sure to pay attention, otherwise, the best $100.00 you will ever spend for your dog!