Features: brand new and high quality Stop Dog Barking: When your dog or neighbor dog keeps barking, gently blow the dog whistle, the ultrasonic frequency emitted by the dog whistle can easily attract the dogs attention and stop barking. Adjusable Frequencies: Different dogs respond to different frequencies. Our dog training whistle has a nut and screw that would adjust the frequency when turned. Notice your dogs reaction to each setting until your dog exhibits the strongest reaction. Absolutely Safe: The dog whistles are made of high-quality copper. Ultrasound frequencies attract the attention of dogs without damaging their hearing and without any healthy problems. Suitable for All Dogs: Silent dog whistle ​suitable for all dog breeds including (Labrador, Golden Retrievers). Value Pack: The package includes 2pcs ultrasonic dog whistles, and 2pcs nylon lanyards with hooks. Specifications: Material: Copper, Nylon Lanyard Style: 2pcsBlack/1pcWhite+1pcBlack Size (Approx.): Whistle 8x0.7cm/3.15x0.27in, Lanyard (Hook Included) Length 49cm/19.29in Weight: Approx. 55g Package Includes: 2 Piece Dog Whistle (2 Style to Choose) 2 Piece Lanyard with Hooks note: 1.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks!