The Power Is In Your Hands. The PWRCORE 20 4.0Ah Lithium Battery is backed by an innovative temperature management system that results in longer run time and battery life. Each cell is surrounded by revolutionary phase change materials to keep the battery cool, and powering through any project. You can use this lithium battery to power up any SKIL 20V power tool! Longer Run Time & Battery Life —The PWRCORE 20 Lithium Battery has an innovative temperature management system to keep the battery cool and powering on through your project Always Know Charge Status—Green LEDs show status, so you always know how much charge is left Power Up 20V Tools—Pairs with any SKIL 20V product