Steelite 21V 4.0Ah Lithium Ion Battery Pack offers powerful, long-lasting performance for a variety of power tools. It ensures extended usage and reduces the need for frequent recharging. Ideal for both home and professional use, it's durable and portable.This battery is sold as a single battery and does not include a charger or a tool. ?Wide Compatibility? Designed specifically to be compatible with all STEELITE 21V cordless power tools. ?Battery Specifications?Features a capacity of 4000mAh, a maximum voltage of 21V, and a power output of 80Wh. ?Safety Features?Equipped with an intelligent protection system and high-quality cells, safe against short circuits, overcharging, discharging, and overheating. It has passed a 1.5-meter drop test for added durability and safety. ?Enhanced Performance? Includes a power indicator light and a heat-dissipating vent design to accelerate battery cooling, ensuring optimal performance and longevity during use. ?Ultra-Low Self-Discharge? Featuring a low self-discharge design to ensure high performance. For optimal lifespan, it is recommended to recharge the battery every 3 to 6 months when not in use.