The Ranger by Zeus Anti-Bark Collar for small dogs safely and humanely helps reduce excessive barking with the gentle use of sound and vibration-pain free & shock free.This collar offers a choice of two different training modes (sound or vibration), which allow you to select the mode that best works for you and your dog.The sound mode emits a high frequency sound that deters dogs from barking; the vibration mode releases a vibration every time your dog barks. Low and high settings allow you to adjust the level accordingly.The Ranger by Zeus Anti-Bark Collar is an excellent way to curb your dog's excessive barking. This collar is also available for large dogs.