Thread the whistle onto a lanyard, cord, or chain
Adjust the length so it sits comfortably at chest level
Place the cord around your neck under or over the trench coat collar
Keep the whistle accessible in a coat pocket if not worn around the neck
Clip it to a lapel, zipper pull, or inner coat loop if available
Secure it so it does not swing excessively while walking
Make sure it is easy to reach quickly with one hand
Check that it does not snag on buttons, straps, or scarf fabric
Remove it before washing or storing the coat
Clean and dry it regularly if worn outdoors