PWR CORE 40 LITHIUM BATTERY – This 40V 4.0Ah lithium battery fuels the power and performance of the PWR CORE 40 system LONGER RUNTIME & BATTERY LIFE – Industry-leading PWR CORE 40 lithium battery technology wraps each cell with cooling material to keep the battery powering on for 25% longer runtime & 2X battery life ONE BATTERY, MANY TOOLS – Pairs with all SKIL 40V power tools ALWAYS KNOW CHARGE STATUS – Green LEDs show status, so you always know how much charge is available SHOCK-RESISTANT DESIGN – Provides additional durability to battery cells and electronics