Original High Quality 21700 Lithium-Ion Battery with 4000mAh capacity and 3.7V output, designed for high-performance power tools, battery packs, and demanding devices. Built with reliable Samsung 40T cell technology, it ensures long cycle life, high discharge capability up to 35A–45A, and stable performance in heavy-duty applications. Perfect for power banks, e-bikes, solar packs, and industrial tools requiring superior energy storage.