Built-in 2200mAh large capacity 18650 battery, durable battery life, environmental safety, effective in teaching Strong and durable, 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