Features: No solder and modulars structure enable quick assembly of this 21700 powerbanks kit, eliminating welding tool and technical barriers for powerbanks creation. for single 21700 lithiums batteries (not included), this ABS builts kit features removable construction with builts in smartests protections against overcharge, overheating, and short circuits. for enthusiasts and nontechnical users way to builds customized portable charging without specializeds skills. for outdoor or emergency charging situations, offering portable power backup for phones, tablets, and wearable devices. Equipped with smartests recognition chip for automatic current adjustment, ensuring safe charging across multiple devices including headphones and smartwatches. Specifications: Materials: Plastic Size: 105x29x25mm/4.13x1.14x0.98inch Color: Black, Light Blue, Beige, Pink, Purplee(optional) Battery type: 21700 battery Package Includes: 1PC Mobile Power Box note: Please allow 0-1cm error due to manual measurement. make sure you not mind before bid. Due to the differences between different monitors, the Pictures may not reflect the actual of the item.