All outdoor enthusiasts must carry a whistle, it is part of your essential mountain safety kit & can be used to attract attention & help rescuers to locate you. The main body of this lightweight version is made from polycarbonate so it wont stick to your lips in freezing conditions. RESCUE SIGNALS SOS: 3 short blasts/flashes, 3 long, 3 short. Repeat after 1 minute interval. MEWS: The Mountain Emergency Whistle Signal is 6 blasts of the whistle with a 1 minute break & then repeated. The reply is 3 blasts with the same pause. Do not stop when you hear a reply but keep blowing until physical contact is made with the rescuers.