Wireless Half-Mile Hailer Kit. Powerful 50 watt PA reverberant horn delivers 108dB sound pressure level over the 584-608MHz audio range. Reach crowds up to 3000. Covers the length of a football field! Lets you see and be seen. Great for athletic events, band practice, field days, public safety, law enforcement, outdoor marketing events crowd control, auctioneers, political campaigns, missionaries - any outdoor event. Includes powerful 50W multimedia stereo amplifier with built-in receiver and lapel/headset mic's with transmitter extra horn speaker, 2 heavy duty tripods and carrying case on wheels. Shoulder strap. Power with Optional AC adapter or power up to 200 hours with 10 D-cell alkaline batteries (not included); or Rechargeable NiCad Battery Pack (requires AC adapter).