Introduced in 1884 - the Acme Thunderer was the worlds first and is still the leading pea whistle. Offering total reliability, control, and power to the user. It is now the worlds best selling whistle, there is not a major league or sport that has not been graced by this whistle. Available in Small (High Pitch) Medium (Medium/High Pitch) and Large (Medium Pitch). Made of Nickel Plated Brass.