Note:Before turn on the voice amplifier, ensure that the MIC don't point at the Speakers amplified, this will eliminate any annoyance associated with howling. For ensure better amplification, aim at the headset MIC capsule when speaking, and keep the distance between the voice amplifier and the MIC more than 60 cm to avoid howling.Simply tucking the speaker around waist, and mounting headphone over head can help achieve the required distance.Specifications:1. Output Power: 15W2. Charging Voltage: DC 5V, 0.5A3. Lithium Battery: 3.7V, 2500Mah4. Working Time:With 50% Volume8~10 Hours (Musical Mode);10~12 Hours (Wired Mic Mode)5. Charging Time: 3~5 Hours6. Product Size: 115*86*35mm7. Unit Weight: 204g8. Available Color: Black9. Working Temperature: -10~4510. Frequency Response: 200Hz~18Khz11. Sound Coverage: 800Main Featuers:1. SHIDU Patented Appearance;2. Stylish, Ergonomic And Comfortable Design;3. High Power Double Magnetic Trumpet --- More Clear And Penetrating;4. Bluetooth 4.2 Chip, Singnal Transmission More Fast And Stable;5. Wired MIC With Built-In Lithume Battery;6. OLED ScreenAdopt 3.5 Inch HiFi Double Magnetic Big-Size Trumpet, Maximum Peak Up To 15W;7. Adopt Shidu Acoustic Amplification Electroacoustic System;8. Equipped With SHIDU Special Acoustic Microphone --- HiFi Original Sound Amplification;9. Super MP3 Audio Encoding Technology --- Support TF Card & U Flash Disk;10. One Touch HiFi Recording;11. Support AUX --- Can Connect With PC And Work As Speaker;12. Support FM Stereo Radio.Standard Package:1 * Main Machine1 * Waistband1 * Microphone1* USB Cabel1 * User Manual Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.