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.
Tin whistle
There are larger whistles, which by virtue of being longer and wider produce tones an octave (or in rare cases two octaves) lower. Whistles in this category are likely to be made of metal or plastic tubing, sometimes with a tuning-slide head, and are almost always referred to as "low whistles" but sometimes called "concert whistles". The low whistle operates on identical principles to the standard whistles, but musicians in the tradition may consider it a separate instrument.