Features: 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. Do not close the cover untill test it is finished, it can not open again if closed. Made of high quality plastic material, it is wear resistant and durable. Perfect for outdoor travel use. Welding Free 3x18650 shells digital display power bank detachable case; Please note that the capacity of each battery must be consistentDo not place the battery upsides down as it will damage the motherboards. (The spring is the negative poles and the spring is the positive poles) Specifications: Material:Plastic Color:Black, Size:Approx.88x77x24mm/3.46x3.03x0.94in Number of batteries: 3x18650 batteries Input:DC5V2A Micro USB+Type c Output:DC5V2A USB Package Includes: 1xPower Bank Case 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.