It can fill 10 pieces of 18650 li-ion batteries. But this is only a shell, there is no battery inside. This product is component without battery core. It is used to repair and assemble batteries pack, only for people who are familiar with battery performance and have practical experience in battery assembly. No Original, new, No Battery Cell !!!!!! Balanced charging fuction: through the battery management system, ensures that the voltage of each battery cell is basically consistent, ensuring that each battery cell is fully , avoiding certain cell voltages being too high or too low, improving energy utilization efficiency, ensuring the performance of the battery pack, and thus extending the service life of the battery pack. Please be kindly noted: If you have any objection to the following two items, please do not order! (1). PCB color may be any color according to our stock, (2). PCB design may change with the same function and performance guaranteed. (3). The number and position of components on the PCB may change and be adjusted. Preparation before assembly: (1). If a new core is used, please note: a. 18650 power lithium battery core must be , b. A group of 5/10 cores must be equipped with resistance and capacitance to make their voltage the same. (2). If the old battery is repaired, please test the voltage at both ends of each cell. If the voltage is different, please charge each cell to the same voltage value. Very important: that the voltage of each cell is the same before welding PCB. Color: Black Material: plastic Package Contents: 1 x lithium battery case 1 x PCB Protection Circuit Board (The color of the protection plate is random, no specified color is accepted) 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.