Our 3rd party tested and safety checked dog whistle with 49cm lanyard and lid features adjustable frequency and frequency lock to stop barking and teaches recalls and tricksDog 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 ageAdjustable Frequency + Frequency Lock: Yes, our dog whistle has more frequencies. Proprietary precision grinding produces a finer frequency range, which is why frequency locking is included so you never lose your dog's perfect pitch.Choose a Better Eco-Friendly Dog Whistle: Yes, we care about quality and the environment. Carefully crafted to be cruelty-free and safe tested with your pet in mind.