Designed for high-demand tools to power through the toughest jobs Innovative temperature and overload protection optimizes the battery and tool during heavy use High performance lithium-ion battery cells Impact resistant overmold increases protection from drops and jobsite debris ...Designed for high-demand tools to power through the toughest jobs Innovative temperature and overload protection optimizes the battery and tool during heavy use High performance lithium-ion battery cells Impact resistant overmold increases protection from drops and jobsite debris Fits Hercules All 20V cordless tools Fits Hercules Extreme Performance lithium-ion battery uses 21700 battery cell technology for more power and runtime.