Features:
Adjustable pitch, 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.
Real metal training whistle produces crisp high tone to teach dogs sit, crouch, stop barking etc, great for professional training.
Adjustable mechanism by screwing or unscrewing the pitch to produce  in different frequency. Especially fit for older and hard hearing dogs. 
Used to train police dogs, dolphin, pigeons, cat and other animals. It can make crisp  by lightly blow. 
Keychain included, A keychain attached to this whistle for conveniently hanging. 
 
Description:
Some tips to use the dog whistle:
Adjust the pitch & 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.
 
Specifications:
Material: metal
Color: Silver
Size: 55x 7.8 x 7.8mm
 
Package Contents: 
1 x Pet Training Whistle with Keychain