unusual cord on men's hat

[yng1998]

This is the first men's hat I have come across with this type of cord.  It starts under the band and has what looks like a button almost at the end of the cord.  The end has a loop and the cord is threaded through this loop.  I am not sure what this cord is for.  Please help.

[bill11223]

The loop goes thru the lapel button of the man's jacket. It keeps the hat from rolling down the street when displaced  on a windy day.

[yng1998]

Thank you so much!!!