Supplier: SDL Imports
A Bosun's call or, Bosun's Whistle, is a pipe or a non-diaphragm type whistle used on naval ships by a boatswain. The pipe consists of a narrow tube which directs air over a metal sphere with a hole in the top. The player opens and closes the hand over the hole to change the pitch. The rest of the pipe consists of a "keel", a flat piece of metal beneath the gun that holds the call together, and the "shackle", a keyring that connects a long silver or brass chain that sits around the collar, when in ceremonial uniform.