Application: 1, help, warning - suitable for outdoor adventure, female, lonely donkey, children, as well as sea rescue 2, warning, command - police, security, vehicle scheduling and management 3, outdoor Contact - (go travel together, one person, in advance of the flute is encoded, then you can be more distant contact), suitable for outdoor sports 4, competitive game - for a variety of sporting events for referees 5, play their usefulness for other purposes