My macbook air is from 2010 and has been a sweet little laptop. It's battery life has been reduced to lasting about 90 minutes from what was once 6-9 hours. I finally ordered a replacement pack on ebay and swapped it out. It's easy work with the right tools. It requires a torx T3 for the outer screws and a torx T4 for the inner ones. Doing this on my own for $60 was way better than the alternative of mailing the laptop to Apple and paying full price + labor for the swap ($129).