Features: This 5S 21V LiFePO4 battery protections board features 2MOSFET design for high efficiency and smart protections against overcharge, over discharge, short circuit, overcurrent, ensuring safe and stable performances for battery tool replacement applications. Designed with a 5s configuration for 21V output, it includes 2MOSFET to minimize energy loss, supports LiFePO4 batteries for superior safety and cycle life, and offer clear connection interfaces for easy installation &maintenance. Ideal for enthusiasts and power tool users who need reliability battery solution for replacing factory packs ,enhancing flexibility. Perfect for home workshops or professional setting where creating secure battery packs for drills cordless tools and cutter requires robust overcurrent and short circuit protections. Engineered with PCB materials, this smart board delivers efficient energy management and thermal protections, making it for long lasting battery systems in various power tool scenario. Specifications: Component: PCB, ABS Size:Approx.6x6cm/2.36x2.36inch Product type: 5s 21V 10A 2MOS Option Type:1pc,3pcs; for power tool, Multiple Protections: Overcharge, over-discharge, short circuits and over-current protections Applicable scenario:Battery packs for modified power tools,Electric vehicles,Energy storage systems Package Includes: Package A 1pc Battery protections Board Package B 3pc Battery protections Board note: Please allow 1-3cm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.