Features:1 、 whistles ( nuclear design 、 greatly increasing the loudness of the whistle 、 nylon lanyard )2 、 refers to the North ( South ) pin ( accurate、 clear )3 、 hygrometer ( ambient temperature a pretty good idea )This little whistle also has a compass、 thermometer function、 another with a lanyard for easy carry. In the wild 、 when these are very necessary tool that can provide timely helpThis product is suitable for tourism 、 meetings 、 outdoor activities and various competitions events.