Friend, 18650 battery is not the same size as AA OR AAA battery, please be well note. If you need battery used in Power Bank, we suggest use flat head 18650 battery.
Features:
* Specially designed for wireless BT earphones, earbuds and headphones with Micro USB ports.
* 300mAh capacity power bank can charge your wireless BT earphones for 5 times.
* Made of high-quality plastic material, durable and shock-proof.
* Mini size and lightweight design make it portable to carry.
* Built-in smart chip automatically matches the rated voltage and current of the earphones without harm.