According to the update, “This update is recommended for MacBook Air (mid 2012 and mid 2013) models. This update addresses rare issues where the battery unexpectedly stops functioning, the system does not recognize the battery, or the system hangs when the battery charge reaches less than one percent.” If you own any of the devices mentioned above and have experienced this rare battery issue, then this update is for you, so you might want to check your software updates to see if it is available for download for your device.