Specifications: Built-in 2200mAh battery can be used compatible 10 days. Portable voice amplifier is designed with large volume and clear sound, and there is no noise. It is suitable compatible teaching, tour guides, parties, lectures, promotions, training, etc. How to use the microphone: When you press and hold the power button, the blue indicator light will light up. Insert the 3.5 plug of the microphone into the corresponding microphone jack of the amplifier, and adjust the volume to achieve the desired sound amplification effect. Special Reminder: In order to achieve normal volume, when wearing the microphone, please aim the direction of the microphone toward your mouth and keep the closest distance. Music Mode: Power on and insert the TF card to play music in the card, and the power light flashes. Previous Song Button: Short press: Previous Song. Long Press: Single Cycle Play/Pause Button: Short Press: Play/Pause. Long Press: Turn On/Off Next Song: Next Song When the host is charged and used under low voltage: When the voltage is too low, the blue light of the power indicator flashes, indicating that the battery is insufficient, but it can still be used. Please charge the host in time. When the voltage is too low, it will automatically shut down. The charging time is about 4 hours. The indicator light will be red when charging, and the indicator light will go out when fully charged. Item Name: Audio Speaker Material: ABS Battery: Built-in 2200mAh Battery (Included) Maximum Power: 8W Distortion: less than 0.5% Frequency: 50Hz - 10KHz Output Resistance: 2 ohm Work Temperature: 10 Degree Celsius - 45 Degree Celsius Working Voltage: 3.7V Charging Time: about 4 - 5H Features: Wired Microphone, Teaching Accessory, No Noise Size: 8.4cm x 9cm x 2.8cm/3.31" x 3.54" x 1.10" (Approx.) Notes: Due to the light and screen setting difference, the items color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Audio Speaker 1 x User Manual 1 x USB Cable 1 x Wired Microphone 1 x Lanyard