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 . TRAINING - Made of & amp ; 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 :(2 Pack) 1 Piece Dog Whistle