The floating ball inside makes the whistle louder than non-ball versions
Includes lanyard
You simply cannot yell, scream or holler louder than a whistle. Uses less energy, too. All hikers, hunters, campers, fishermen and outdoor enthusiasts should have one with them. Always keep one in your emergency kit, too.
Hot tip: The standard signal for needing emergency help... 3 short blasts in a row.