Features: Featuring advanced 21V balanced protections board technology with temperature controller, this battery accessory ensures stable charging/discharging cycles to extend battery service life and optimizing power tool performances. Crafted from PC, the housing resists impacts and abrasions while maintaining structural integrity in demanding work environment. For professional craftsmen and DIY enthusiasts requiring reliable power solution for extended operation of for tool. Ideal for construction sites, workshops, and industrial setting where battery accessories withstands daily wear from power tool applications. The integrated 5Mos3 alloy circuit and intelligent temperature management system deliver consistent power output while preventing overheating during intensive tool operate. Specifications: Material: PC Size: about. 10x7cm/3.94x2.76in Package Includes: 1pc Balanced protections Board note: Please allow 1-2cm errors due to manual measurement. Due to difference between different monitors, the picture may not reflect the item actual color.