1. With self-recharge battery, it is easy for use in every place. 2. With echo function. With the gain control and the exciter control. 3. With tie bar wireless microphone; MP3 input and Earphone monitor. 4. It can input the music signal and the microphone signal at the same time. Specifications:(1) Guitar Input Impedance: 220kW (2) Output T.H.D: less than 2%(3) Output power: 30W (4) Woofer: 8 inch speaker(5) Size: H33cm x W33cm x L18cm (6) Input sensitivity: -60dB more than 5mV (7) Frequency Response: 600Hz - 1.4KHz + or -3dB