Toshiba is upping the ante in the microSD card department, launching new high-end cards that they're calling the "world's fastest". Using the new UHS-II SD card specification, these microSD cards are designed for 4K video recording, giving cameras too small for a full-sized SD cards the storage speed they need.
The cards will be available in 32 GB and 64 GB capacities, the former packing maximum transfer rates of 260 MB/s during read and 240 MB/s during write, and the latter with 145 MB/s read speeds and 130 MB/s write speeds. Toshiba claims the 32 GB model is eight times faster than the company's existing 32 GB UHS-I microSD card, which is a pretty significant improvement.
These new microSD cards are rated for UHS Speed Class 3, indicating minimum write speeds of 30 MB/s, which makes the small form factor storage suitable for sustained 4K video capture for the first time. The UHS-II specification supports theoretical maximum transfer rates of 312 MB/s, so Toshiba isn't reaching the speed barrier just yet.
One of the most interesting aspects of UHS-II class microSD cards is the physical interface it uses. To achieve such high speeds, an extra row of eight pins is required below the standard set of pins, meaning that to achieve the full capabilities of the cards, you'll need a device that's UHS-II compliant. Chucking one of these microSDs into a non-UHS-II device will see it run at typical SD speeds well below what the cards are capable of.
Toshiba are shipping samples of these new microSD cards to other manufacturers at the moment, but it shouldn't be too long before they're widely available, likely at a high price point.