The Hailer family is great for use in high noise areas and large open spaces. Use it to direct emergency crews and alert crowds. It covers a football field! And unlike megaphones which cover your face, the Half-Mile Hailer lets you see and be seen. Great for crowd control, public safety, law enforcement, ath - letic events, band practice, field days, outdoor marketing events, auctioneers, political campaigns, missionaries - any outdoor event.