4K video recording is quickly becoming a standard on all new recording devices, we also know that 8K is just around the corner.  The SD Association announced faster SD specifications to support the speed needed for up to 8K recording a couple of years ago with the UHS-II speed class, and while we have seen several SD cards, there haven't been many MicroSDXC cards released that support the higher speeds.  High speed cards are needed for recording on the latest recording devices such as GoPro's, Yi 4K+, drones and similar devices. https://www.youtube.com/watch?v=HZSf2bKp9P0 Lexar is one of only a couple of manufacturers that has started to release UHS-II high capacity MicroSDXC cards.  Lexar's 128GB 1800x MicroSDXC card (part number LSDMI128CRBNA1800R) is rated for up to 270MB/s sequential read speed, and 100MB/s write speed; of course having the fastest MicroSDXC card will cost you, currently it can be purchased online at various etailers for $166.95 plus shipping.  The nice thing is that Lexar also includes a MicroSDXC to SD adapter, a USB 3.1 Gen 1 MicroSDXC card reader and a free copy of Image Rescue 5 (downloadable) for that price.  If 128GB is larger than you need, they also offer the card in 32GB and 64GB versions; which actually have a faster write speed up to 250MB/s. [caption id="attachment_199460" align="aligncenter" width="645"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - Retail Packaging[/caption] Included in the retail package is not only the MicroSDXC card, but also a UHS-II SD adapter, and a USB 3.1 Gen 1 Type-A MicroSDXC card reader.  In addition to the card, we also picked up the Verbatim USB-C Pocket Card Reader (part number 99236) that supports UHS-II cards to test the SD adapter, however we found that while it would read the UHS-II card, it did not take advantage of the higher speed capabilities of the card, this is why it is nice that Lexar included the MicroSDXC card reader in their packaging. [caption id="attachment_199461" align="aligncenter" width="645"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - Packaging Contents[/caption] The UHS-II specifications calls for a second row of contacts on the memory cards, similar to how USB 3 includes a second row of contacts to allow for the higher speeds. [caption id="attachment_199462" align="aligncenter" width="645"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - Back of Cards[/caption] We will test these new cards on a desktop system with an Intel Core i7-6700K, with an ASUS Sabertooth Z170S motherboard which has a USB 3.1 Gen 2 Type-C and Type-A ports.  Testing will be done with ATTO v.3.05, CrystalDiskMark 5.2.2 and a real world drag and drop write test with a large video file. ATTO Disk Benchmark showed that the Lexar Professional 1800x MicroSDXC card was running beneath the rated speeds, with a maximum of 251MB/s on the read test, and 88MB/s on the write test.  While it is beneath the rated speed, it is not unusual to see performance numbers vary slightly, but provides a good idea on the speeds you should expect.  However, this does show that the tine MicroSDXC card is fast. [caption id="attachment_199463" align="aligncenter" width="474"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - ATTO Results[/caption] With CrystalDiskMark, we received faster scores than ATTO.  Here the Sequential Read maxed out at 265MB/s, while the Sequential Write came in at just under 101MB/s. [caption id="attachment_199464" align="aligncenter" width="407"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - CrystalDiskMark Results[/caption] Finally, we conducted a "Real World" file copy test, where a 14.2GB MKV video file of a 4K movie that we copied from a Samsung 950 Pro M.2 PCIe NVMe drive to the Lexar Professional 1800x MicroSDXC card.  The file topped out at 115MB/s, but averaged 114MB/s.  Throughout the write process the speed was extremely stable with barely any drops in speed; the few times it did drop it would only go down by a few MB/s.  Transferring the 14.2GB file took around 2 minutes and 20 seconds which is pretty fast for a MicroSDXC card. [caption id="attachment_199465" align="aligncenter" width="645"]Lexar 1800x UHS-II u3 MicroSDXC Lexar 1800x UHS-II u3 MicroSDXC - Real World 14.2GB 4K File Copy[/caption] Final Thoughts and Conclusions [caption id="attachment_199822" align="aligncenter" width="645"]Lexar 1800x MicroSDXC Lexar UHS-II 1800x MicroSDXC[/caption] The Lexar Professional 1800x is rated for up to 270MB/s Read and 100MB/s Write, this is the fastest 128GB MicroSDXC card we have seen. However, it's not the fastest of the UHS-II cards, the 32GB and 64GB versions of this card actually has a faster rated write speed of up to 250MB/s!   In our testing with ATTO, CrystalDiskMark and a 4K video file copy test the tiny 128GB MicroSDXC card worked great and came in just under the rated Read speed by 5MB/s, while the rated Write speed was exceeded by up to 15MB/s. The SD Association has released a new speed rating for recording video, designated by a Vxx.  Lexar doesn't list the V rating on this card, however it should receive the V90 speed designation.  If you look at the SD Association's speed ratings, the speed of the Lexar 1800x exceeds the speed needed to record 4K video, it matches the speed necessary to record 8K video! Lexar Professional UHS-II MicroSDXC 1800x Pricing: If speed isn't a huge concern, there are cheaper alternatives to the Lexar Professional 1800x 128GB MicroSDXC card; you could go with a slower card or a higher capacity card.  However, if you want the biggest and fastest MicroSDXC card, you won't go wrong with the Lexar Professional 1800x 128GB. LR Recommended Award Legit Bottom Line:  If you are wanting to get one of the fastest MicroSDXC cards currently available that will work for video recording up to 8K, the Lexar Professional 1800x should be on your radar.  It includes a great little card reader that actually takes advantage of the high speed capabilities and a SD adapter card designed to work specifically with this MicroSDXC card.