ThinkPad Battery 55+ (6-cell)

Carry battery spares, or replace system batteries when charge capacity diminishes with time.
Features

57 Watt-hour battery energy
Weighs 340 g (0.75 lb)
Combine this battery with the ThinkPad Battery 27++ (9 cell slice) to provide an all-day computing experience
ThinkPad External Battery Charger (40Y7625) compatible