Hey guys,
We are from TheMiniDrive.com.
Currently, NiftyDrive (our competitor) is the only company offering a MiniDrive for the 13" RETINA MacBook. We are working on releasing one, but it is not ready yet. Thanks for emailing us BTW, but at the moment NiftyDrive is your only option for something that fits
If you are interested, what differentiates these "short-microSD adapters" is the length. If you are ok with something sticking out the side of your laptop than you can get a longer adapter card. For the MacBook Retina 13", you need a card that is 16mm long. The 'generic' cards listed above are much longer and will stick out by about 6-7mm, the PNY will stick out by about 8mm and our shortest MiniDrive card will stick out by about 3mm. We do offer a new MiniDrive (not linked above) that will stick out by about 1mm, however NiftyDrive's card is designed for the 13" Retina MBP, which none other is (at least until we can get ours released!).
For people with other MacBooks, our newest MiniDrives are focused on 128GB integrated flash memory (NOT-microSD). We did this to increase speeds. Our non-microSD based MiniDrives are about 25% faster than MiniDrives with microSD cards. We source the same premium chips as the leading brands - they work great! We also are the only company to offer a MiniDrive for the New 15" Retina MBP - which customers have loved!
Thank you again for the email! Please continue to send suggestions

Best of luck with you 13" Retina, no matter what you choose!