Features: For side light 18650 batteries, this 21V protections board features intelligent balanced charging technology to maintain uniform cell voltages, significantly extending battery lifespans while ensuring optimal performances. Engineered with high thermal conductivity PCB materials and multiple model compatibility, it delivers efficient heat dissipation and seamless integration with various tool configurations. Ideal for professional contractors, electronics technicians, and enthusiasts requiring power management solution for heavy duty equipment and precisions projects. Perfectly suited for extended operations in demanding environments like construction sites, automotive workshops, and outdoor maintenance tasks where battery stability is critical. Incorporates advanced safety mechanisms including overcharge/over discharge protections and short circuit prevention, offering peace during high intensity usage with toolless installation convenience. Specifications: Materials: PCB Size: 85x60mm Color: Yellow for 21V voltages environment, specially for side light 18650 battery, with protections function Package Includes: 1PC 21V Balanced Circuit protections Board note: Please allow 0-1cm error due to manual measurement. make sure you not mind before bid. Due to the differences between different monitors, the Pictures may not reflect the actual of the item.