I would say that these whistles are some of the smallest and loudest whistles on Makerworld, the smallest being only 15mm x 6mm diameter

I wanted to see how far I could push the boundaries with a 0.4mm Nozzle.

Each of these whistles will produce over 100db + with the tiniest whistle producing 113db on trial.

These will fit comfortably on a key chain etc.

See the images with a Standard peg as a comparison.

Small Parts warning: Due to the size and loudness of these whistles, they are not suitable for children under the age of 5.

Thanks for Looking.