Shepherd's whistle
They are also produced commercially. Simple whistles may cost less than 1 USD in bulk; expensive ones may be quite ornate. They are commonly made of plastic, aluminum, stainless steel, silver, brass, titanium, Corian, jade, buffalo horn and other materials.
Whistle tip
Whistle tips, also referred to as whistler tips, or whistlers, are modified vehicle exhaust pipes that generate a whistling sound during the operation of a motor vehicle that can often be heard up to a mile away.