Features: Battery Voltage: 18V Battery Capacity: 6000mAh / 9000mAh Battery Type: Lithium-Ion Compatible with Milwaukee 18V Cordless Power Tools and Chargers Electronic control charge and discharge analysis to optimize performance and extend service life. Built-in chip prevents protection against over-discharging, overcharging and short-circuiting. No memory effect, can be loaded or unloaded as needed without loss of capacity. 4 LED light shows the amount of electricity Compatible Part Number : 48-11-1811, 48-11-1815, 48-11-1820, 48-11-1822, 48-11-1828, 48-11-1840, 48-11-1841, 48-11-1850, 48-11-1852, 48-59-181, 48-59-1850 Compatible With: For Milwaukee M18 Cordless Lithium-Ion System Tools 2646-22CT, 2643-21CT, 2641-21CT, 2646-21CT, 2646-20, 2642-21CT, 2641-20,.