Today we are testing the ProGrade Digital USB 3.1 Gen 2 Dual-Slot SD card reader. This reader is rated officially as having a combined max transfer speed for both cards of 1250MB/s (although as we will see later on this isn’t exactly a realistic number for a dual UHS-II reader).
Build and Design
The card reader is fairly small measuring 7cm (2.5″) by 7cm, is very well built, and has a really strong magnet that will stick to any metal enclosure which is a really nice touch.
The card slots are a bit too close to each other in our view and the unit is just a little bit too short to be really comfortable to take out the cards comfortably but this is a minor nuisance.
On the back of the unit, you have a single USB-C connector and the unit comes with two cables – UBS-C to USB-C and USB-C to USB-A as well as a nice metal plate with the ProGrade logo.
Testing Rig
For our testing, we got two of ProGrade’s fastest SD cards – 64GB and 128GB versions of the company’s SDXC UHS-II, V90 cards with a rated read speed of 250MB/s and write speed of 200MB/s with a minimum guaranteed transfer speed of 90MB/s. We also used two of our SanDisk UHS-I and UHS-II cards and our beloved, but aging, Lexar UHS-I USB 3.0 SD/CF reader for comparison.
Dual slot SD UHS-II memory card reader
We ran a number of different tests on the cards, all of them on our new and fast studio computer connected to a USB-C port )just a reminder, our brand new fast studio has a Core i9-9900K processor, 32GB of RAM an Asus RTX 2070 GPU and Z390 Gigabyte DESIGNARE motherboard with built-in dual TB3 ports one of which we used for most of the tests in this review and two Samsung 970 NVME drives we also used to prevent bottlenecking our test running the latest win 10 Pro).
Tests
All tests included transferring a folder with close to 5GB of video files from the card to the computer and back measuring the transfer time and average speed.
- ProGrade card reader (USB-C) – 1 X ProGrade Card (128GB) – The average transfer speed to the computer from the card was 245MB/s (20 seconds) and from the computer to the card, we got 195MB/s (25 seconds). Both very close to the official speed of the card.
- ProGrade card reader (USB-C) – simultaneous ProGrade cards (64GB + 128GB) – The average transfer speed of the first card to the computer was 204MB/s (24 seconds) and the second card was 244MB/s (21 seconds). The other way around got us 204MB/s (24 seconds) from the first card and 214MB/s (23 seconds) on average from the second card. This means that the combined average transfer speed of the reader with both these cards was around 450MB/s (using USB-C to USB-C), not really maxing the speed of each card individually (that would be closer to 500MB/s) but still extremely fast.
- ProGrade card reader (USB-C) – single SanDisk card (UHS-II) – The average transfer speed to the computer from the card was 272MB/s (18 seconds) and from the computer to the card, we got 222MB/s (22 seconds). Please note that this is one of Sandisk’s older UHS-II cards – the current generation is rated at 300MB/s read and 260MB/s write.
- ProGrade card reader – single SanDisk Card (UHS-I) – The average transfer speed to the computer from the card was 90MB/s (54 seconds) and from the computer to the card, we got 80MB/s (61 seconds).
- USB-C-USB-A speeds (dual Prograde UHS-II cards) – Using a USB A connection (USB 3.1) we got only 168MB/s (29 seconds) for each card simultaneously, that is 337MB/s combined – still fast, but pretty far from the 450MB/s we got with USB-C (TB3 supported connection) on our motherboard.
- Lexar UHS-I USB 3.0 card reader (single card UHS-I (Sandisk) / UHS-II (Prograde 128GB)) – Our aging Lexar reader was a bit slower reading the UHS-I Sandisk card with 87.5MB/s (56 seconds) to the computer and 77MB/s (63 seconds) to the card. Being a UHS-I only card reader you can easily see how it bottlenecked the UHS-II Prograde 128GB card with 85MB/s (57 seconds) to the computer and 75MB/s (65 seconds) back to the card, obviously much, much slower than the ProGrade reader.
Conclusion and Pricing
Let’s conclude. The ProGrade card reader sells for $80 and at this price, it is a fantastic option for anybody who needs to offload two UHS-II cards at the same time at blazing fast speeds.
Even if your current camera doesn’t support UHS-II, but you are shooting lots of high res videos and want to save time offloading them to your computer, getting a UHS-II card is a very good idea and if you are using two cards each time with different content (stills and video for example), the ProGrade reader will provide almost the max limit of each card at the same time which can be worth a lot of wasted time with a single memory card reader.
The ProGrade card reader
As for the ProGrade UHS-II cards. Since we got the ones that we have been using in this review the company came out with a newer version that officially does 300MB/s read and 250MB/s write which seems almost identical to the current generation of SanDisk UHS-II cards, although the top ProGrade cards are rated at V90 or a minimum of 90MB/s, unlike the SanDisk UHS-II cards which only officially promise a minimum sustained write speed of 30 MB/s.
Since at the moment the ProGrade (128GB at least) is about $10 cheaper than the SanDisk ($190 vs. $200 of the 128GB Sandisk UHS-II card) we see no reason not to go for the ProGrade card.
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Iddo Genuth 
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