My husband maxed out his SSD on his 11" MacBook Air (late 2010). I wanted to double the SSD as a Christmas present. That then allowed me to install a game he wanted which was also a Christmas present.
The screw drivers I used were from the 54bit Driver Kit. Being metal drivers, they did not strip when I tried to remove the housing screws from the bottom like the ones I got from another supplier. I was able to easily remove the screws on the back of the the MBA with ease, replace the SSD and return the back as if it had never been removed.
Use the metal driver bits vs. the drivers with the plastic tips. At least do this when you need to remove the screws from the bottom of any MacBook device. The screws are in pretty tight. Thank you iFixit!