For small dogs 3.6 kg to 11.3 kg (8-25 lbs), neck size 17.7 cm - 35.5 cm (7” - 14”) Batteries included (3 x L44 1.5 volts). The Ranger by Zeus Anti-Bark Collar for large 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.