I love the features that it offers such as the whistle pitch is adjustable, and very simple to use, simply tighten or loosen the screw to determine the frequency. Also I thought that it was silent, nope, I was wrong. I like also that it is lightweight, and can be worn on a lanyard around your neck, as this is what I have done instead of placing it on my keys. Plus it comes with a small e-book that gives you types on how to use it correctly for your furbaby.
Plus as a bonus, the company is offering my readers a $5.00 off coupon to purchase their product so here is the link: www.raminaturals.com/dogtrainingwhistle and the Coupon Code is: LOYALDOG
If you would like to check out what others have said, or even purchase one for you self, check out the following link: http://www.amazon.com/dog-training-ultrasonic-sound-whistle/dp/b00psqy5h0
I received one or more of the products mentioned above for free using Tomoson.com. Regardless, I only recommend products or services I use personally and believe will be good for my readers.