Introducing the 21700 Battery Charger with Power Bank Function, your ideal companion for charging 21700 Li-ion batteries and powering your devices on the go. This versatile charger is designed to meet your daily charging needs with high efficiency, safety and convenience. Specially engineered for 3.6V/3.7V rechargeable 21700 Li-ion batteries, it is fully compatible with protected 21700 batteries, providing a stable and reliable charging experience (battery not included). With a maximum 3A fast charging speed, it significantly shortens the charging time, while the intelligent current matching function ensures safe charging: it automatically adjusts the charging current based on the battery's IR, using small current for dead or nearly full batteries to avoid overcharging and extend battery life. What makes this charger stand out is its dual function: it works as both a 21700 battery charger and a portable power bank. Simply insert your own 21700 battery, and you can connect your phone, flashlight, camp light, headset and other USB-powered devices to charge them anytime, anywhere—perfect for travel, camping, hiking, or daily use when you need extra power. The practical design adds more convenience to your use. The Type-C (USB-C) input port is widely compatible, and the included USB-C cable can be used to charge most other devices during travel, eliminating the need to carry multiple cables. The specially customized adjustable strap fits different 21700 batteries tightly, preventing any shaking or falling during charging or use, ensuring stability and safety. Package includes 1x 21700 Battery Charger, 1x USB-C Cable, 1x Adjustable Strap, and 1x User Manual (battery not included). We are committed to providing high-quality products and reliable after-sales service. If you encounter any problems during use, please feel free to contact us via Amazon or our official team, and we will respond to you within 8 hours. Choose with confidence, and enjoy efficient, safe and convenient charging!