Stay unplugged longer with these genuine Think Pad batteries. These rechargeable batteries use Lithium-Ion technology & can be used as replacement for aging system batteries or as a convenient spare battery. Features Lithium-Ion (Li-Ion) technology 9 cell system battery Battery energy (Watt-hours): 94 Wh Compatible with the Think Pad External Battery Charger (40Y7625) Compatible with X220, X230