Features: 【Broad-Spectrum Compatibility Design】Compatible for 21V power tools, this balanced protections board ensures perfect pairing with 18650 batteries. 【High-Efficiency Heat Dissipation Structure】Constructed from premium PCB with exceptionally thermal conductivity, effectively preventing overheating. 【Intelligent Balance LED】Features an integrated balance LED light displaying real-time operational display for clear visibility. 【Lightweight Portable Design】Convenient to carry and install, not adding extra burden while enhancing work efficiency. 【Durable Side-Lighting Design】Unique side-lighting construction enhances product durability and service life. Specifications: Component: PCB Size about 6x3.2cm/2.36x1.26in Power tools suitable for 21V 18650 batteries, such as angles grinders, electric wrenches Quantity: Single Set contains 1 protections board Practicality: Provides battery balance protections Package Includes: 1PC Balanced protections board note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.