Can the 480GB SanDisk Ultra II be used in a Macbook Air (13" mid 2012) to replace original Disk Driv

HI, 

I have a Macbook Air 13", mid 2012.

I believe it has a 128GB SSD; and was wwanting to reolace it with a larger/newer SSD.

Will this SSD work to upgrade the MacBook Air?

Thanks

Hello, 

yes the ssd will work normally and fine in your macbook, so no worries about that. 

Yes, but when you get the drive you will need to manually format (erase) it using Disk Utility - most SSDs are formatted using Windows partition maps. Using Disk Utility, you want to erase the drive and use OS X Extended Journeled (AKA HFS+) or its encrypted counterpart. After formatting, you then either install OS X onto the drive using a bootable USB media, or clone your current hard drive onto the new SSD using a program such as Carbon Copy Cloner (CCC is among the best, IMO.)

If you use a bootable USB drive, it is very easy to make them for the current build of El Capitan, and the install process itself is simple. When you swap out the drive, be very gentle with the SATA cable because they are especially delicate on MBPs from this era.

Finally, after you install the drive, enable TRIM using the Terminal via command line. Otherwise, the SSD will progressively slow due to garbage accumulation.