A simple emergency whistle is an invaluable tool in the event of trouble in the backcountry. This lightweight model from Montbell creates a piercingly loud 3000 Hz tone and has a bright color, so it's readily located when needed. The whistle also includes a card for your emergency contact information, which stashes in a small compartment at the back of the whistle and is easily found by responders. It comes with a short lanyard for attaching to a pack strap.