Features: The BMS4S 16.8V lithium batteries protections board ensures safe charging with overcharge protections and cell balancing for 4s 18650 batteries, enhancing performances in highly demand applications. Features advanced overcharge prevention, balanced cell charging, and a user friendly PCB design for seamlessly integration into customs battery packs. Ideal for enthusiasts and professional creating reliability power solution for electric tool or customs energy systems. Perfectly suited for upgrading cordless power tools, solar energy storage, or building high performances battery packs requiring stable 16.8V output. Engineered with durability PCB materials, this 4SBMS module maintains consistent battery health while supporting demanding applications 16.8V. Specifications: Component: PCB Size:Approx.34x34mm/1.34x1.34inch Applicable voltages: 16.8V Number of Battery Connection: 4s Applicable scenario:Flashing drill,Garden electric scissors; Option Type:1pc,3pcs; Package Includes: Package A 1pc 18650 Battery protections Board, Package B 3pc 18650 Battery 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.