The SanDisk microSD UHS-II Reader (SDDR-339) is included with SanDisk Extreme Pro UHS-II MicroSD cards. It offers high-speed USB 3.0 compatibility for maximum transfer speed. It is compatible with microSD, microSDHC and microSDXC cards and supports both UHS-I and UHS-II. Few card readers have the separate row of pins necessary to connect using the UHS-II interface; in many readers UHS-II cards will only operate in UHS-I mode at lower speed. Having a dedicated UHS-II microSD reader is necessary to take advantage of the additional speed offered by UHS-II microSD cards.
The external case of the SanDisk microSD UHS-II Reader is black plastic with a brushed metal insert on the top. The end of the reader is slanted and has a single microSD slot. A small hole below the microSD slot will accommodate a string to attach it to a keychain. There is no card access light.
When a microSD card is inserted into the reader only about 2.5mm of the card remains outside, just enough for a fingernail to catch on the small raised portion at the end of the microSD card. The reader measures 1 5/16 x 3/4 x 1/4 inches (33 x 19 x 6mm). It is practically the same overall size as the microSD card readers included with Lexar microSD cards.
The SanDisk microSD UHS-II Reader reached up to 242.0 MB/s sequential read speed in benchmark tests. A read speed of 239.4 MB/s was reached using the SanDisk Extreme Pro UHS-II 64GB microSDXC card. The highest sequential write speed using UHS-II cards was measured at 211.6 MB/s using the Lexar Professional 1800x 32GB microSD UHS-II card. Using UHS-I microSD cards, the reader offered speeds up to 94.3 MB/s sequential read and 88.2 MB/s sequential write.
Comparing several microSD in the SanDisk microSD UHS-II reader with other micro UHS-II readers (including size SD UHS-II readers with SD to microSD UHS-II adapters), the performance of this SanDisk microSD reader is on par with most. Only two Lexar readers, the Professional Workflow SR2 and LRWM04U-7000, offered significantly higher read speeds.
Few readers support UHS-II microSD cards, making a dedicated reader a practical necessity to take advantage of the additional speed offered by UHS-II. SanDisk probably had this in mind when the decision to include the reader with the Extreme Pro UHS-II microSD cards was made.
Reader: SanDisk microSD UHS-II USB 3.0 Reader
Benchmark: CrystalDiskMark 3.0.3 x64
Program settings: 1000 MB, 5 passes, random test data
Operating system: Windows 10 Pro
Motherboard: Gigabyte GA-Z77X-UD3H
Processor: Intel Core i7-3770K @ 4.40GHz
RAM: 32GB DDR3 1600
SanDisk microSD UHS-II USB 3.0 Reader Card Benchmarks | Sequential Read (MB/s) | Sequential Write (MB/s) |
---|---|---|
Lexar Professional 1800x microSD UHS-II 64GB | 243.742 | 205.482 |
Lexar Professional 1800x microSD UHS-II 32GB | 242.026 | 211.556 |
SanDisk Extreme Pro UHS-II 275MB/s microSDXC 64GB | 239.374 | 105.586 |
Lexar Professional 1800x microSD UHS-II 128GB | 238.557 | 105.459 |
Lexar Professional 1000x microSD UHS-II 32GB | 151.748 | 52.836 |
Lexar Professional 1000x UHS-II microSD 64GB | 150.636 | 53.279 |
Lexar Professional 1000x UHS-II microSD 128GB | 144.991 | 58.892 |
SanDisk Extreme 90MB/s U3 V30 microSDXC 128GB | 94.569 | 63.969 |
SanDisk Extreme Plus 95/90 MB/s microSD 64GB | 94.254 | 88.197 |
SanDisk Extreme 100MB/s A1 microSDHC 32GB | 94.068 | 71.914 |
SanDisk Extreme Plus 95/90 MB/s microSD 32GB | 93.816 | 88.079 |
SanDisk Extreme Pro 95MB/s microSDXC 64GB | 93.681 | 87.681 |
SanDisk Extreme 90MB/s microSDHC 32GB | 93.665 | 48.962 |
SanDisk Extreme Pro 95MB/s microSDHC 32GB | 93.656 | 87.200 |
SanDisk Extreme Plus 80MB/s microSD 32GB | 93.631 | 65.307 |
Transcend 633x microSDHC 32GB | 93.248 | 83.900 |
Samsung PRO Select microSDXC 64GB | 93.198 | 84.122 |
Kingston U3 (90/80) microSD 64GB | 93.058 | 83.685 |
PNY Pro Elite microSDXC 64GB | 93.041 | 84.823 |
Patriot EP PRO microSDXC 64GB | 93.000 | 84.115 |
Kingston U3 (90/80) microSD 32GB | 92.844 | 83.639 |
Patriot EP Series microSDXC 64GB | 92.803 | 86.480 |
PNY Elite-X microSDHC 32GB | 92.737 | 75.863 |
Transcend Ultimate 633x microSD 64GB | 92.671 | 84.508 |
Samsung EVO Select microSDXC 256GB | 92.606 | 83.960 |
Samsung EVO Select microSDXC 64GB | 92.573 | 25.156 |
PNY Turbo Performance microSDXC 64GB | 92.532 | 57.037 |
Samsung PRO Plus microSDXC 64GB | 92.467 | 84.358 |
Samsung PRO microSDXC 64GB | 92.443 | 78.275 |
PNY Elite microSDXC 128GB | 92.402 | 28.449 |
PNY Elite-X microSDXC 64GB | 92.296 | 73.776 |
PNY Turbo Performance U3 microSD 32GB | 92.280 | 54.537 |
SanDisk Extreme 90MB/s microSDXC 64GB | 91.675 | 43.462 |
SanDisk Ultra 90MB/s microSD 200GB | 90.566 | 20.682 |
Samsung PRO Plus microSDXC 128GB | 90.130 | 83.532 |
Samsung PRO Select microSDXC 128GB | 89.960 | 83.181 |
Lexar Professional 633x microSDXC 200GB | 88.607 | 34.726 |
SanDisk Ultra 80MB/s microSD 64GB | 84.912 | 20.532 |
Lexar Professional 633x microSDXC 128GB | 84.515 | 22.525 |
Samsung EVO Plus 128GB microSDXC | 83.579 | 22.630 |
SanDisk Ultra 80MB/s microSD 32GB | 82.578 | 17.173 |
Samsung EVO Select microSDXC 128GB | 81.449 | 22.432 |
SanDisk Extreme U3 microSD 32GB | 74.626 | 53.997 |
PNY Elite microSDXC 64GB | 69.186 | 24.580 |
Lexar Professional 633x microSDXC 64GB | 68.773 | 19.024 |
SanDisk Extreme U3 microSD 64GB | 68.054 | 56.044 |
SanDisk Ultra microSD 64GB | 46.440 | 15.827 |
SanDisk Ultra microSD 32GB | 46.375 | 14.698 |
Samsung EVO microSDXC 64GB | 46.352 | 23.466 |
Samsung EVO microSD 32GB | 46.334 | 24.529 |
SanDisk Ultra 80MB/s microSD 128GB | 35.020 | 29.359 |
The SanDisk microSD UHS-II Reader (SDDR-339) is not currently available for purchase separately. It is included with SanDisk Extreme Pro UHS-II microSD cards such as the Extreme Pro 275MB/s 64GB microSDXC UHS-II card.