Specification：

Battery Type: Li-ion
Voltage: DC-20V         
Capacity：4000mah

Features：

Top A Grade Battery cells; 
Built-in integrated microchip prevents overcharging and over heating;
Could charge and discharge upto 300 cycles
Built-in fuel gauge lets you know how much power you have before it needs recharging 
Flat standing base,With this convenient design, you can keep your tools standing in an upright position. 
Built-in cooling channel: Help cooling battery cell down while working and charging
More power: This extra large battery holds over 2 times more power than the other,

smaller models