Pedy Dog Whistle to Stop Barking with Loud Sound Repellent Repeller Safest Dog Obedience, Repellent, and Training Aid Silent Bark Control for Dogs Ultra-sonic Sound: The whistle can produce an ultra-sonic sound that is easier for dog to hear, it's a great way to train your dog. It's actually an effective tool for training the dog to follow your commands Effective but Silent: The whistle is silent, its designed only for dogs. so its no need to worry about annoying others with the whistle sound. Please be patience to adjust the pitch & blow the whistle to your dog (dogs can't hear all frequencies) Warranty: We offer 30 days money back or free replacement and 24 months warranty