This 4.0Ah battery is compatible with all Hyper Tough 20V tools. You will never run out of runtime while having this additional Hyper Tough Battery on hand! Lithium-Ion Batteries have a high energy density which provides a longer discharge time and provides consistent power through the charged cycle. Unlike NI-Cad batteries which slow down as energy is depleted, these Lithium-Ion batteries run full strength until all energy is expended. Once charged Lithium-Ion batteries also have a longer shelf life and will not lose power when not in use. This battery is sold as a single battery and does not include a charger or a tool.