Roland BA-55 Powered Speaker Cabinet Portable design with high-quality sound for audiences up to 80 people. SPL (sound pressure level) rated at a powerful 108 dB One 2.4 GHz wireless microphone included (DR-WM55); a second DR-WM55 can be purchased separately for simultaneous use Operates on 8 AA batteries or AC power (AC adaptor included) Three-channel built-in mixer with two-band EQ. Echo/Reverb effect. Built-in Anti-Feedback function. Line Output for recording or expanding the system