1. This model has no button, cannot insert a card, cannot insert a U disk to play, no Bluetooth function, just a pure amplifier. 2. High volume, anti-whistle, long battery life 3. 5W high volume, cares for the voice, easy to control the whole field 4. Frequency shift noise reduction adaptive technology, high fidelity, low noise, even at high output power, will not produce significant distortion 5. With headset, comfortable to wear, not easy to fall off 6. Built-in 1200 mAh lithium battery, up to 12 hours of battery life Parameters: 1. Power: 8W (MAX) 2. Signal-to-noise ratio: 83dB 3. Charging voltage: DC5V 4. Input power: USB power supply 5. Distortion: 1% (3.7V, 1KHz, 1W) 6. Impedance: 2Ω 7. Speaker: 2.5 inch x 1 8. Operating temperature: -5-40 degrees Celsius 9. Product size: 85 x 38 x 39mm 10. Weight: 160g Packing List: Amplifier x 1 Head-mounted wireless microphone x 1 USB data cable x 1 Belt x 1 User Manual x 1