Apple OEM Battery for MacBookAir 11" (from 2011 to 2012)
Part No: A1406, Li-ion battery with Power Rating 4680mAh
Brand new Replacement battery 4680mAh compatible with all 2011 to 2012 MacBookAir models
Warranty: 1 year incl 7%gst and courier delivery in Singapore.
STEP by STEP guide how to replace the MBAir 11" battery, go to this site:
https://www.ifixit.com/Guide/MacBook+Air+11-Inch+Mid+2011+Battery+Replacement/6306