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USB 3.0/eSATA Dual 3.5” SATA III Hard Drive External RAID Enclosure w/ UASP and Fan – Black

Create an external dual 3.5in HDD SATA RAID array, connected through either USB 3.0 with UASP or eSATA

Product ID: S3520BU33ER

  • UASP Support (Attached SCSI Protocol Specification Revision 1.0)
  • eSATA or USB Host Connection
  • Compatible with SATA revision I/II/III (1.5/3.0/6.0 Gbps)
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  • Hardware RAID
  • Plug-and-Play Compatible
  • Dual Drive Bay
  • Built-in Fan
$82.99 USD
63+ In stock
In stock
US: 61 | CA: 2
In stock
Where To Buy

Technical Specifications

Warranty Information
Warranty 2 Years
Chipset ID JMicron - JMS562
Compatible Drive Types SATA
Drive Installation Fixed
Drive Size 3.5in
Fan Bearing Type Ball Bearing
Fan(s) Yes
Fans 1 - 40 mm
Interface eSATA
USB 3.0
Number of Drives 2
Number of internal 3.5 inch bays 2
Hot Swap Capability Yes
Max Drive Capacity Currently tested with up to 4TB 7200 RPM hard drive
MTBF 30,000 hours
Port Multiplier Yes
Supported RAID Modes BIG (Spanning or Concatenation)
JBOD - (Just a Bunch of Disks)
RAID 0 (Striped Disks)
RAID 1 (Mirrored Disks)
Type and Rate USB 3.0 - 5 Gbit/s
SATA III (6 Gbps)
UASP Support Yes
Drive Connectors SATA Data & Power Combo (7+15 pin) Receptacle
Host Connectors eSATA (7 pin, Data) Female
USB Type-B (9 pin) USB 3.0 Female
Microsoft WHQL Certified Yes
OS Compatibility OS independent; No software or drivers required
LED Indicators 1 - Enclosure Power LED
1 - Drive 1 Activity LED
1 - Drive 2 Activity LED
Center Tip Polarity Positive
Input Voltage 100 - 240 AC
Output Current 3 A
Output Voltage 12V DC
Plug Type M
Power Consumption (In Watts) 36
Power Source AC Adapter Included
Humidity 20%RH ~ 80%RH
Operating Temperature 5°C to 35°C (41°F to 95°F)
Storage Temperature -20°C to 50°C (-4°F to 122°F)
Physical Characteristics
Color Black
Material Aluminum and Plastic
Product Height 3.3 in [8.5 cm]
Product Length 6.9 in [17.6 cm]
Product Width 4.4 in [11.3 cm]
Weight of Product 21.9 oz [620 g]
Packaging Information
Package Height 5.5 in [14 cm]
Package Length 10.1 in [25.6 cm]
Package Width 7.1 in [18 cm]
Shipping (Package) Weight 3 lb [1.4 kg]
What's in the Box
Included in Package 1 - USB 3.0/eSATA HDD RAID enclosure
1 - eSATA cable
1 - USB 3.0 cable
1 - universal power adapter (NA,EU,UK)
1 - rubber foot set
1 - instruction manual
Supports any operating system.
No additional drivers or software required.


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USB 3.0 / eSATA 4-Bay 3.5in SATA III Hard Drive Enclosure w/ built-in HDD Fan & UASP – SATA 6Gbps

Add four 3.5" SATA III hard drives to your computer externally through USB 3.0 with UASP or eSATA

25+ In stock In stock
US: 17 | CA: 8
In stock Learn More


USB 3.0/eSATA Dual 3.5” SATA III Hard Drive External RAID Enclosure w/ UASP and Fan – Black

Customer Reviews

3.3 (9 reviews)
3.3 out of 5 stars
Quality of Product
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1 - 9 of 9 Reviews

(5 stars) Excellent as system backup

By: Mike M
I have had one for aver a year and it works well. I only use it for system backup so it's only on for a few hours about once a month. It does have a noisy fan. Next version should have a larger diameter lower RPM fan to keep the noise down.
Comment Helpful? Yes - 0 No - 0 Report

(1 star) Not Working

By: DeadDave
I bought this enclosure to had 2 internal drive after I downsized my case on the plus size it was very easy to fit the drives, Once booted up {and set To Jbod} my computer sees the drives in device manager but nothing is happening they don't appear in file manger or even in disk manager
Comment Helpful? Yes - 0 No - 0 Report
Response from
Brian, Customer Support
Thanks for sharing this feedback. We're sorry the drive enclosure hasn't worked well and we'd like to help. This might happen if the drives are coming from another operating system or RAID (Redundant Array of Independent Disks). We'd like to know more about your configuration so we can look into the issue further. We have free, Technical Support ready 24 hours, 5 days a week, should you encounter any problems. We can even arrange a remote support session to look at the issue along with you. To contact our Technical Support team, please click on Support at the top of this web page.

(4 stars) Compact, speedy, and easy to use.

By: Nick_132
Undo one screw to access the insides. Press one button to change the RAID settings. It's THAT easy to use. Comes with both types of data cables, which I tried out and work just fine. Also used a USB-C to eSATA cable from Startech, and throughput to the box was just as it should be. Strangely I need to comment on how happy I am about the power brick. The AC side is a simple 2-prong cable instead of a big brick, so no fighting for power-strip/outlet space! The DC side cable is a really decent length too. The overall size of this device means it can be on the desktop yet out of the way, or you can easily place it on top of a tower PC out of the way. So using this with my newer XPS tower (which SUCK for only having internal bays), I've got tons more storage I can switch around, or even boot into. :) The only two critiques I have are: 1. Fan is a bit noisy for such a small thing. 2. I'd like to see some plastic 3.5 to 2.5 adapters included. Just my own two cents there. I used the box with 3.5" drives and tried all the modes and it was great. Then I had to fabricate my own drive adapters to use SSDs in a more permanent use case. With so many SSD options out there in the 2.5 size... including adapters by default would have put me over the edge to buy these for several uses! I received this product in exchange for an unbiased review.
Comment Helpful? Yes - 1 No - 0 Report

(4 stars) Noisier than expected

By: ShawnO_8
I am happy with the ease of setup and the overall functionality however the fan is extremely loud for the size of the unit. The enclosure is very light weight even with both drive bays filled, however the drives don't feel very securely mounted and may be contributing to the overall noise. Not my favourite product but it certain performs as expected if you can overlook the noise issue. I received this product in exchange for an unbiased review.
Comment Helpful? Yes - 2 No - 0 Report

(5 stars) Great simple storage

By: Andrew11
I’ve had a few of these kinds of desktop storage devices over the years, they are usually big, heavy and cumbersome. This unit is none of those. It’s not much bigger than two 3.5in drives stacked on top of each other, the drives just slide in from the front without a carrier, and setting up the RAID is done by sliding a switch on the back and holding the “Set Raid” button while turning it on. Simple! The unit is only as noisy as the HDDs you put into it. There is a small fan inside that you can hear when there aren’t any drives in it, but once you load it you can’t hear it at all. I like the look of the unit with the LEDs on the front showing power and activity, and I tried several large file transfers which were fast as I needed them to be with USB3. Nice to have the ESATA but I haven’t tried it yet. Build quality is good, with large rubber feet to minimize vibrations. For the List price, I think this unit provides good value for what it does. I received this product in exchange for an unbiased review
Comment Helpful? Yes - 1 No - 0 Report

(4 stars) Good.

By: nivek
I used this with RAID and eSata connection with Windows 10. I did not experience the problems referenced in other reviews. I did notice that it was a bit loud for my quiet office.
Comment Helpful? Yes - 1 No - 0 Report

(2 stars) Needs work to be a contender

By: macphoto1970_001
This product is not what I would call one of's better products. The unit I received has a very very loud fan. Now I am not sure how loud this is supposed to be but I find the noise excessive. Drives install easy enough but they do not screw in, lock down or any type of security. The drives rattle a bit when you move the unit. I think some of the noise i hear is vibration from the drives! I dont think this will be good for the drives long term. The setup was easy, I tried using the combine feature and it worked without a hitch. Just move the switch to the drive setting you want, Hold in the set button and turn it on. Voila. I then formatted the drive for use with Apple and again no issues at all. I have viewed other comments about disconnects but I have not experienced this under OSX. The device works...the build quality is almost there..but the noise from fans, vibrations, is just too much. I received this product in exchange for an unbiased review.
Comment Helpful? Yes - 4 No - 0 Report

(3 stars) Buggy

By: campingintherain
I am using JBOD, not RAID. With the USB cable Win10 will recognize and write to both of the HDD that I have in this enclosure (4TB and 6TB). However, the unit will shut itself off after a period of inactivity, so large copy operations should be monitored in case a file being open will pause the copy operation (e.g. Outlook .pst file if email client is open). I read in a review that this doesn't happen with the eSATA cable, however, with eSATA Win10 will only recognize one of the two drives I have installed. Enclosure has great potential but falls short.
Comment Helpful? Yes - 1 No - 1 Report
Response from
Sam, Customer Support
Thank you for your feedback on S3520BU33ER. We're sorry for the trouble you've had with it and would like to help. We don't expect the S3520BU33ER to shut itself down after a short period of inactivity. This behavior could be the result of power-saving features in Windows 10. These may include the "Allow the computer to turn off this device to save power" checkbox in the Device Manager and the disk sleep settings in Power Options. We recommend contacting us directly so that one of our Technical Advisors can look into this further for you. You can reach us 24 hours a day, 5 days a week, at 1-800 265-1844 or

(2 stars) Good speed when it's not disconnecting

By: nrshap
Seemed to work well but disconnects from the computer (Windows 10) once a day or more (and you then need to power cycle it to reconnect). Finally one of my drives was reporting errors so I tried moving data to another drive on the computer itself. It was a 6GB drive and the during the transfer it kept disconnecting until I finally got fed up and removed the drive from the enclosure. Put it in a different brand enclosure and the transfer is going well now. I may try to upgrade the firmware, but the download doesn't have any details about what's been fixed, and basically I don't trust this enclosure anymore.
Comment Helpful? Yes - 0 No - 1 Report
Response from
Malcolm, Customer Support
Thanks for taking the time to leave your feedback. We apologize our S3520BU33ER seems to be causing intermittent issues in your setup, and want to help. The firmware just corrects a bug related to how the enclosure is labeled in Device Manager in various RAID modes. It doesn't affect actual unit functionality. The enclosure has a 2 year warranty and free lifetime technical support. Please chat with us at so can troubleshoot and potentially help you get the dock replaced if needed.
By: jlmedina
Same issue With windows 10 and USB3. eSATA works fine... Har disk tested with another USB3toSATA adapter and performs fine.
Helpful? Yes - 0 No - 0 Report