Oternal No Bark Collar with an Integrated Dual-Mode Dog Training Device (Beep and Vibration, Beep and Shock), an no Hurt Dog training Collars for the Dogs Weighing 15-60 lbs (No shock collar) High-quality Electronic Anti-Bark Dog Collar and Sends no hurt and no pain warning beep and vibration(no shock) to the dog whenever it barks. Effective on a Puppy and Medium-small Sized Dogs Weighing 10-25 Pounds, use it for the big dogs/ large breed is no obvious effect The stimulations repeat through 7 correction levels, the intensity gradually increases until the dog stops for thirty seconds. If the continuous stimulus reaches the 7 levels, then the collar will stop working for 1 minute to protect the dog 7 sensitivity levels (1-7) adjustable for the different size of dogs barking, the more sensitive, the easier it goes off. Unique bark terminator, Lightweight receiver, Replaceable 6-volt Battery. Troubleshooting steps and other pertinent information: 1.The collar doesnt go off when the dog barks? A: 1) Low sensitivity for some small size dogs can cause go off insensitively, you can increase the sensitivity to higher level, set the sensitivity to level 5-7; 2Make sure place the collar snugly underneath the dog's neck, and not on the side of its neck;3) Red lights flashing, or you may hear only beeps without vibration indicate the battery needs to be replace 2. Doesnt work on the dog, which still barks after using? The stimulus( beep and vibration( no shock)) is a soft warning, it is mainly effective the 10-25 lbs dogs, dont use it for the big dogs( exceed 25 lbs);3. The collar would beep and vibrate to the dog under the other behaviors, such as shaking head, scratching. A: You can turn lower the sensitivity, set it to level 1-3. 4. More problems in use, you can see the latest manual, as shown in Fig.6 in the listing