The idea behind this type of whistle is that it won't disturb anyone standing right there with you. While these types of whistles can be heard by humans, a dog's hearing goes further into the ultrasonic range than a human's so they will be out of human hearing range.
The whistles are adjustable so that you can tune it to a frequency that gets the best response from your dog.
Produces ultra high frequencies in the range of 5800 Hz to 12,400 Hz
1 x Dog Whistle