[Type of battery] Lithium-ion. Voltage: 20V. This battery pack contains 10 pieces 3.6V 18650-2000mAh Lithium-ion batteries. [Compatible with DURATECH 20V tools] Well compatible with DURATECH 20V cordless power tools such as drill, impact driver, impact wrench. More tools soon, stay tuned. [Power indicator] 4 indicator lights on the battery pack for recognizing battery charge status immediately. [Much safer] Safe guard features against incorrect voltage, battery overload, short circuit, internal overheating. No memory effect, can be charged freely. [Environment friendly] Innocuous to the environment. All 10 pieces lithium-ion batteries in the battery pack accord with certification requirements of CE/GS/EMC/PAHS/ROHS. DURATECH 4.0 Ah Li-ion Battery Pack for 20V Cordless Impact Power Tools