This rugged, dependable whistle was developed for the US Navy.  Attach to a life jacket, foul weather gear or other personal protective equipment.  Compactly molded of high impact plastic.  Resists weathering and corrosion.  The loud (116 db), shrill whistle is audible from great distance and facilitates locating overboard victims.  Flat design will not hold water.  Meets SOLAS requirements