MicroSD cards are a popular form of external storage for some Windows and Android phones and tablets, but there are limits to how much you can keep on an 11-by-15mm card. Up until now, you could only add an extra 64GB of storage via microSD, but SanDisk is changing all that with the 128GB SDXC card that it announced Monday at the Mobile World Congress in Barcelona.

To boost capacity, SanDisk said in a statement that it had "developed an innovative proprietary technique that allows for 16 memory die to be vertically stacked," and each memory die is "shaved to be thinner than a strand of hair." The new card will be available exclusively through Amazon.com and BestBuy.com initially, and as a Class 10 SD card it offers minimum read and write speeds of 10 megabytes per second. This should be sufficient for recording 1080p video, according to the SD Association's speed ratings.

Getting this kind of storage capacity in this kind of package won't come cheap, though. Sandisk's MSRP for the new microSD card is $199.99, about $1.56 per gigabyte: that's well over what you'd pay for a modern SSD or a standard-size 128GB SD card, the latter of which you can get on Amazon for about $80 as of this writing.

As time goes on and prices come down, the ability to fit so much extra storage in a space-constrained phone or tablet will be handy for the digital hoarders among you. One of the first devices to explicitly support the new card is Samsung's Galaxy S5, which was announced earlier today.