HAOYI 100 percent 30-Day Money-Back Guarantee: Yes, its a fact. Our 3rd-party tested and safety inspected Dog Whistle with 49cm lanyard and cover features adjustable frequencies and frequency lock to stop barking, and teach recall and tricks Please return for a full refund if youre not 100 percent satisfied - no questions asked Dog Whistle Stops Barking, Teaches Recall and Tricks: Yes, weve developed a better dog whistle to stop barking and help train your dog. More frequencies mean better results for any pooch, at any age Adjustable Frequency and Frequency Lock: Yes, our dog whistle has more frequencies. Proprietary precision grinding results in a finer frequency range, which is why Simply Natural includes a frequency lock so you never lose your dogs perfect pitch. Choose a better Eco-Friendly Dog Whistle: Yes, we care about quality and the environment. The Simply Natural Dog Whistle crafted cruelty-free and safety tested with your pet in mind try and youll see, or get your money back with our 30-day 100 percent money-back guarantee, no questions asked.