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fatmac wrote: ↑Sun Nov 13, 2022 3:51 am Very nice - but these aren't 'telescoping' whistles, these are 'separable', (there is a difference).

Definition of telescope:
Parts that slide one within another and are thus capable of being extended or shortened.

The Hoover and O'Brien whistles both telescope. The manufacturers describe them as telescoping whistles.

Both whistles were photographed disassembled to show the build quality, and both are also shown in collapsed mode. To use, they telescope open to the scribed marks on the tubes.

Because of their design, both are also tunable.

Actually....

telescoping
adjective

Capable of being extended or compacted, like a telescope, by the sliding of sections or parts one within the other; telescopic; ; -- a term replacing the formerly used telescope.

the GNU version of the Collaborative International Dictionary of English.
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(My highlighting)