The HART 20V 4.0Ah Lithium-Ion battery is an excellent addition, or start to, any DIYer’s HART tool collection. This battery is compatible with all HART 20V power tools. It features Lithium-Ion technology to give you long-lasting and fade-free power to get you through any project you decide to take on. This battery is designed to be compact and lightweight for more maneuverability and while reducing user fatigue. This battery is sold as a single battery and does not include a charger or a tool.