Powerful 4.0 Ah Lithium+ battery delivers up to 10% more performance & up to 95% more run-time, Fuel gauge displays remaining battery charge so user can manage their workload, Intellicell technology monitors & balances individual cells to maximise run-times, storage life & safety, Tough pack design with built in impact protection for long term durability, Part of the One Plus system & compatible with all One Plus tools, new & old.