Acme Official Scout Master Whistle 50.5 6.5cm (2.56 inches)long, medium tone. It's larger than the Acme Official Guides whistle. The mouthpiece allows it to be gripped by your teeth or lips. Has a solid ring and is marked "Scout Master".
Approved in 1909 by Lord Baden Powell and his sister Agnes, founders of the World Scouts and Guides. Unlike conventional whistles, the Scouts and Guides whistles have their own individual sound. They are exclusive to those groups and part of the tradition.