Powerful yet lightweight Federal Signal Voice Guns®. Electronic megaphones with special noise concealing microphone improves voice reproduction. Manufactured with rugged, high-impact Cycolac ™ parts for long service life. Ideal for industry, fire, marine, athletics, law enforcement and many other applications. Model HM738 is made of Lexan ™ high-impact, self-extinguishing plastic. This benefit makes it appropriate for hazardous environments such as oil refineries and other industries where fire hazard is always present. The HM738 operates on eight "AA" batteries (not included).