The 6-Cell Lithium-Ion 70+ Think Pad Battery from Lenovo is a rechargeable lithium-ion battery. It can be used as a spare battery or replacement for aging batteries. This battery is compatible with Lenovo T410/20/30, T510/20/30, W510/20/30 & L Series Think Pads. Features Lithium-ion technology 6-cell system battery 57 Watt/hr battery energy Rechargeable with the Think Pad External Battery Charger (40Y7625)