This whistle comes with an ebook dog training manual, which is actually very helpful for anyone who is trying to train their pet. It not only includes training guidance but also tips and advice. I'm very glad that the ebook points out that physical punishment is never necessary.
The whistle itself is very easy to use and effective. I'm still in the process of training Dotty with it, but she does hear me a lot better when I call her to come in after potty time using the whistle. I like that the pitch is adjustable, however, the screw doesn't always stay where you put it (there is no lock feature), so I would have to use a rubber band or something to keep it in one spot. So my only suggestion for improvement is to have a way to lock the pitch into place once you find one you like. (Although I do see how one might want to use different frequencies for different commands, in which case different notches or a way to mark the pitches would be helpful.)
I also want to point out that the whistle is audible so humans can hear it too, which is to help with adjusting pitch. It's nice because then you know it's working. And you don't have to whistle really loud with it, the dog will hear the ultrasonic sounds even at a quieter sound.
I love how lightweight the whistle is and that it comes on a key ring, plus it's small enough to fit in a pocket. I keep mine by the door so I can call Dotty back in easily.
Overall, this is a handy and effective tool for training dogs that anyone can use.
Disclosure: I received this product in exchange for an honest review. No other compensation was given.