Features: Note that the capacity of each battery must be consistent. Do not inverts the battery as it will damage the motherboards. (The spring is the negative poles and the plate is the positive poles) Please insert it correctly. There is no chance of secondary disassembly, and the shells cannot be disassembled again. Please fix it all at once! Simply install the battery into the slot and correctly connect the connector to build a complete power bank. The 3x18650 Battery Storage Box is a must have for DIY enthusiasts, allowing you to create your own power bank with ease. 18650 batteries are not included in the package, you need to purchase separately. Can only use the 18650 battery of which positive electrode is flat top. This Power Bank Case with 4charging cable is more easy to charge your mobile devices; Equipped with USB charging cable, convenient fully charged anywhere; Specifications: Material:Plastic Number of batteries: 3x18650 batteries Color:Black,White;(Optional) Size:Approx.99x66x33mm/3.9x2.6x1.3inch Input:1Type c Port,2USB Port; Output:Type c Charging Line,Micro Charging Line,Phone Charging Line; Power:5V2A Package Includes: 1xPower Bank Case (Battery not include) note: Please allow 1-2cm errors due to manual measurement,please make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item