The dog whistle has adjustable for active control of the frequency produced. When you blow on the whistle, you can hear the secondary sound made by the air forced through the metal tubing.

Description:

Condition: Brand new
Color: Silver
Length: 2 1/8 inch
Key loop included
Adjustable simply tighten or loosen the screw to work out your dogs frequency
It should be noted that this whistle is audible to the human ear, essential for gauging its efficiency.

Some tips to use the dog whistle:

Adjust the & blow the whistle to your dog. Even dogs can't hear all frequencies. Wait until he is asleep and gently blow on the whistle. Your whistle has a nut and screw that adjust the frequency when turned. Continue testing until your dog perks up. You will then know you have reached a frequency he can hear.
Use the dog whistle with varying sequences to train your dog. For example, one long burst can mean "come," while a series of short, staccato bursts might mean "sit." Keep your whistle commands consistent and your dog will always know what you expect of him.
The dog's behavior according to your instruction need to be trained. Such as, at meal time, blow on the whistle before they get the food. It will only take a few times of doing this and your dog will react quickly.