Built-in 2200mAh large capacity 18650 battery, battery life, environmental safety, effective in teaching Strong and , combined with double layer, 3.5 plug with high strength metal, PVC wire tensile strength, good shielding U disk TF card double jack, can be linked to computer tablet phone Plug in the memory card /U disk can be a single cycle, listening to songs or learning, this function can repeatedly play the same clip Suitable for teaching/tour guide/party/speech/promotion/training and other scenarios Product name: Multi-function loudspeaker Input signal: microphone Battery capacity: 2200 mah 18650 battery Usage time: 20 hours Charging time: 3 hours Scope of application: teaching/tour guide/headset microphone/conference/training/listening to music size: 9.2 x 8.4 x 2.8cm Material: ABS colour: A-Black Package Contents: 10 x loudspeaker 10 x headset 10 x strap 10 x Charging cable 10 x English instructions Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.