Make the coach referee so easy, the electric whistle gets rid of the traditional way of blowing a whistle with your mouth, more sanitary, labor-saving, three different tones switch by the button, sound loud, clear, strong and easily recognizable. The cylinder design make sound goes more far distance. 4*CR2032 batteries include, battery can replace, comes with a neck string lanyard, whistle comfortable to grip, crack-resistant and fall-resistant ABS shell. It must be an awesome high volume electronic whistle for P.E. teachers, basketball coaches referees, outdoor camping, dogs training, hiking lifeguard SOS survival emergency. Tips please don’t put it near the ear when open it.