Feature:1. Rechargeable mini amplifier with headphone output, analog circuit with excellent sound quality.2. The AUX function allows connection to playback devices such as smart phones or MP3.3. Can connect an external mixer or sound controller via XLR or 6.35mm sockets.4. The device can be charged via USB connection, and the USB near red light indicates that the device is charging.5. After the device is fully charged, the red indicator light will go out, and 4 green indicator lights indicate that the power is turned on.Specification:Item Type: Headphone AmplifierInput: 6.35mm guitar input, 3.5mm AUX inputOutput: 6.35mm output, 3.5mm headphone output, XLR outputPower Supply Mode: USB chargingPower Supply: 1 x 18650 battery (not included in delivery)Product Size: Approx. 8 x 11.5 x 2.7cm or 3.1 x 4.5 x 1.1inNote: The amplifier can be charged via a USB connection. The red light is on to indicate that it is charging, and the red light is off to indicate that the device is fully charged..Package List:1 x Exerciser1 x USB Cable 1 x 3.5mm Audio Cable1 x English User Manual Note:1. Excluding battery and power adapter.2. When inserting the battery, please pay attention to the position of the anode and cathode.3. There is no English user manual for bass models.