I present my small keychain survival whistle, which emits a clear and sharp signalling note.
This whistle is of single-piece design and therefore does not need the small plastic insert which some other metal whistles require, that can work loose and fall out.
The attachment hole is 2mm wide and is perfect for a 10mm split ring (not included).
There are some more photos of this object and other examples of my work, both 3D printed and otherwise, on my
'Tofty' facebook page.