This combined whistle contains 3 different shapes and sizes of whistle, just like a family, adults and kids. High sports referee whistles make a loud crisp sound by blowing air out through your lips, or when air or steam is forced through a small opening. AMBITION JUMP Whistle with pea cork inside is made of solid stainless steel, which comes with a black lanyard in a well-wrapped package. It can be a great gift for coaches, referees, officials, police, PE teachers, lifeguards,women self defense, also it can use as emergency survival whistle when you go hiking, camping, exploring, boating, or even meet bear.