Features: Experience rapid charging with this 18650 battery 21V 6 a fast charging protections board, drastically reducing wait times for device recharging. Equipped with multiple safety protections including overcharge, over discharge, and short circuit prevention, it enhances battery longevity and durability using quality PCB for stable performances. Ideal for professional and enthusiasts who frequently rely on power tool and need long lasting, reliability battery solution in their daily tasks. Perfect for harsh work environments or scenarios requiring frequent battery replacements, compatible for 21V 6 a 18650 battery tool household appliances and professional equipment for versatile application. With its flexible design and easy installation, this board offer user friendly adaptability for seamless integration into any setup. Specifications: Component: PCB Size:Approx.86x62mm/3.39x2.44inch for 21V 6 a 18650 Lithium Batteries Craftsmanship: High-precise circuit design to ensures stable performances Support 21V voltages, 6 a fast charging function Suitable for portable equipment and projects, providing overcharge, over-discharge and short-circuit protections to extend battery life Package Includes: 1pc Battery Charging Protections Board note: Please allow 1-2cm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.