The MacBook Air is so thin it's hard for it to have a large solid state drive. So instead of using the traditional thick hard drives with moving parts, PNY has an easy way to boost your MBA's storage using it's integrated SD card slot.
The SD card is available in 64GB and 128GB capacities, and will set you back $100 and $200 respectively. It's a better way than having to swap in a larger SSD drive.[PNY