Description: EASY DOG TRAINING WHISTLE - Adjustable frequencies dog whistles allow you to easily teach your dog/puppy unlimited commands such as stop barking , sit, come, lay down,stay and more. CONVENIENT TO CARRY – small and light weight, You can take it with you to everywhere. ADJUSTABLE FREQUENCIES - Different dogs respond to different frequencies. Our dog training whistle has a nut and screw that would adjust the frequency when turned. TIPS - THE VOICE of the dog whistles are not to be silent, Just the voice is quieter. many people can not hear the sound of this whistle clearly , BUT THE DOGS CAN .Don’t worry about it. SAFE TRAINING - Made of SAFE & PREMIUM MATERIAL,Doesn’t hurt or bother the dog, it just grabs him attention and he stops the annoying barking. Specification: Material: Copper Metal Length: approximately 5.5 cm / 2.2 inch Package Includes: 1 Piece Dog Whistle