The Pet Life Anti-Bark Dog Collar is Water Resistant and Utilizes a specific Ultra-Sonic Frequency Vibration that Safely Reduces or Completely Eliminates Dog Barking. This Anti-Bark Collar also has an Audible Setting that can be turned On/Off that further helps Decrease Barking. The Collar is also Adjustable and suitable for All Dog Neck Diameter Sizes. This Ant-Bark Collar is an appropriate Safe and Healthy Alternative to training your dog. Maximum neck circumference: 17.5 inches.