my hooman got this whistle for us about a year ago. I am a service dog and we are partners. we also use the talking pet buttons but this is the real communicator for us. when my hooman sends certain tones I know what job I am supposed to be doing. when we hike, I can hear this for long distances. when we are in the big cities - I can hear this over loud noises like street construction. we originally got the idea from the book chaser by John W. Pilley Jr. which is about a border collie who had a really special hooman partner and from watching amazing shepherd videos on youtube. as a service dog, this is a tool that has now become essential in our daily lives. if only there was a way to learn from another hooman how to train my hooman to use this more effectively as we are going to start training more service dog/hooman teams and this whistle will become an essential part of the partnership between dog and hooman.