The P108 is the strongest battery in the Ryobi One+ lineup. With this P122 2-Pack, you're doubling up on that power. At a whopping 4 amp hours, these will serve your needs in a variety of applications. Being the flagship battery for the One+ family, you can be sure that it will work for over 70 18V power tools from Ryobi. Additionally, it has an onboard fuel gauge. At the push of a button, you'll be able to see how much charge is left, so you can prepare other batteries as needed. This beast of a battery can go from empty to full in as little as 60 minutes! Unlike its NiCad cousins, the lithium ion design prevents drain when not in use, so you don't have to constantly keep it charging. Simply plug it into your tools when you need it, and rest assured in its reliability. Remember, Ryobi means power done right.