Generic Replacement IBM Battery for THINKPAD T20 T21 T22 T23 BATTERY For use with the IBM ThinkPad T Series, T20 Series, T21 Series, T22 Series, and the T23 Series Laptop / Notebook Models. Alternate part numbers: 02K6620, 02K6621, 02K6626, 02K6627, and 02K6649. Specifications: 10.8V 3600mAh Comes with a 90 day replacement warranty