Our 3rd party tested and safety checked dog whistle with 49cm lanyard and lid with adjustable frequency and frequency lock to stop barking and teach recalls and tricks- No questions ask a dog whistle to stop barking, teach recall and tricks: Yes, we have developed a better dog whistle to stop barking and help train your dog. More frequency means better results for any dog at any age Adjustable frequency + frequency lock: Yes, our dog whistle has more frequency.Proprietary precision grinding produces a finer frequency range, which is why Simply Natural includes frequency locking so you'll never lose your dog's perfect pitch. Choose a Better Eco-Friendly Dog Whistle: Yes, we care about quality and the environment.