I believe that is a beeper, dogs can be trained on them just as
a whistle. Have no experience with them. My dad was a great
bird Hunter, he always had at least 3 dogs, English Setters mostly. He had the shock collar set up to use on young dogs
that were ranging to far or running off after other game. He used
it sparingly. When my brother got old enough to hunt, he put
shock collar on brother and gave the controls to the dog.