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Express 4M2
4-Slot NVMe M.2 SSD Enclosure with SoftRAID

Mac / PC / Thunderbolt 3
Infinitely configurable. Infinitely reconfigurable.
You like to explore your own independent path, and digital storage is where you have fun, push hard and spark the imagination. You explore, you refine, and when ready, you share your vision with the world. The OWC Express 4M2 is the external drive built for the journey before you and the path yet to be explored.

Customize your Express 4M2 with up to four NVMe SSDs, RAID them however you wish and connect it all with Thunderbolt 3 — the fastest and most flexible interface around. The sheer performance of the Express 4M2 helps you meet deadlines faster, giving you more time to explore your creativity and push your projects further.
Pint-Sized Powerhouse
Small in stature. Big on capability. The OWC Express 4M2 is ready to serve with four easy-to-access NVMe M.2 SSD slots customizable for any workflow with vibration damping feet that allow for vertical or horizontal orientation. Install up to 32TB of capacity and experience up to 2800MB/s of mind-bending performance via Thunderbolt 3. The Express 4M2 is an amazingly small digital workhorse with world-renowned OWC quality and award-winning support built in.

Ingest and duplicate dailies at breakneck speeds, work with higher resolutions, smoothly scrub through demanding timelines, and plow through thousands of photos with ease. The OWC Express 4M2 is one seriously fast drive to have by your side to take your digital capabilities to a new level.
Built Smaller and Faster from Input by Pros Like You
The OWC Express 4M2 is designed with superior ease-of-use in mind. We worked with award-winning creatives and listened to the kudos they heaped onto the OWC ThunderBay mini, and we put all that shared knowledge to good use when we set out to build the next-gen Thunderbolt 3 multi-bay drive. The result is the 57% smaller and 2.5x faster OWC Express 4M2.

It's smaller and easier to fit into your workflow, studio and on stage. It's faster with four easy-access M.2 slots so you can swap, upgrade or expand your Express 4M2 to configure and reconfigure it to serve any project need.
Game-Changing NVMe SSD Performance
NVMe (Non-Volatile Memory Express) is a hyper-efficient communications interface protocol built from the ground up to properly take advantage of SSD technology and high-performance connection buses like PCIe. The result is exponentially faster and efficient SSD storage, and the OWC Express 4M2 has room for four NVMe SSDs.
Display connection flexibility is yours with a convenient DisplayPort located right on the rear of the OWC Express 4M2. There's no need to worry about adapters or extra long cables. Just plug your display directly into the Express 4M2 and you're all set.
The OWC Express 4M2 comes equipped with OWC SoftRAID which provides the amazing capability to RAID across multiple drive enclosures. You can also add more Express 4M2 drives to your storage pool using Windows Storage Spaces. Configure and reconfigure your storage however you need by combining multiple OWC Express 4M2 drives together on Mac and Windows.
Includes SoftRAID XT: Easy and Complete Drive Management
SoftRAID XT is the most powerful, intuitive software RAID utility on the market. Multiple RAID options let you select the RAID level that fits you or your project’s needs best. If you need maximum volume capacity, optimum drive performance, data protection, or a combination of attributes, SoftRAID has you covered.
Packed with features like drive validation, verification and failure prediction—SoftRAID includes features you simply don’t get with hardware RAID. It’s like having a datacenter on your desktop! From home users looking to protect photos and documents to professionals needing to protect and quickly access projects, SoftRAID is the perfect solution.
  • Compatible: Works with macOS 11 Big Sur, M1 Macs and Windows 10
  • Advanced: Create RAID 0/1/4/5/1+0 (10) with Macs, RAID 0/1 with Windows machines
  • Protected: SoftRAID Monitor constantly watches your disks and alerts you if problems are detected
  • Validated: Volume validation ensures sectors can be read and parity is correct
  • Certified: Checks disks before use to ensure they are safe for data storage
  • Vigilant: Error prediction helps protect against unexpected failure
  • Universal: Move SoftRAID arrays seamlessly between Macs and PCs with built-in OWC MacDrive technology
SoftRAID provides a level of performance that you simply can’t get with hardware RAID. Learn more about the power of SoftRAID XT.
Connect to Thunderbolt and Thunderbolt 2 Systems with Ease
The OWC Express 4M2 is fully backward compatible with Thunderbolt and Thunderbolt 2. Utilize Thunderbolt 3 performance to work at full speed, and step back to Thunderbolt or Thunderbolt 2 whenever connectivity compatibility is needed for your workflow. Add a Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter along with the appropriate Thunderbolt cable, and you're all set.
OWC Thunderbolt 3 Cable
OWC Express 4M2 comes with an OWC Thunderbolt 3 cable which is Thunderbolt certified for Mac and Windows, with additional 0.5 meter to 2.0 meter lengths available separately.
Quality You Can Trust
Like all OWC drives, the OWC Express 4M2 is built to the highest standards of reliability and performance and Thunderbolt Certified for Mac and Windows. Because 100% reliability is always the goal, Express 4M2 is rigorously quality tested and backed by our one-year limited warranty plus award-winning, 24/7 customer support.
Your Digital Life…Protected for FREE
Backing up and protecting your data is critically important. But all too often it’s a task that falls to the bottom of the “to do” list, and you don’t realize it until it is too late. That’s why OWC has partnered with Acronis to give you 1 full year of the #1 personal backup and antivirus software to integrate into your workflow.
Acronis Cyber Protect Home Office safeguards you from today’s data threats—from accidents to failures to attacks. With easy, intuitive backup and Ai-enhanced antimalware technology, your digital life is protected—photos, files, applications, systems, and the devices they are on.
  • Complete Backup and Fast Recovery: quickly restore your files or entire system at any time
  • Easy Disk Cloning and Full Image Backup: just two clicks to start a full disk image backup
  • Cloud, Local or Hybrid Cloud: back up locally, to the cloud, or both. It’s your choice

Learn more about Acronis Cyber Protect Home Office

Product Specifications

  • Mechanisms Supported
    • NVMe 2280 M.2 SSDs
  • Display Support
    • Up to one 4K display @ 60Hz,
    • or one 4K display @ 30Hz,
    • or two 4K displays @ 60Hz
  • Display Support by Port
    • Mini DisplayPort 1.2: Up to 4K @ 60Hz
  • Bootable
    • All four drive bays are bootable on macOS. SSDs with 512 byte sectors require macOS 10.13 or later.
  • Hot Plug Support
    • Yes
  • Chipset
    • (1) Thunderbolt 3 - Alpine Ridge DSL6540
  • Certifications
    • CE
    • FCC
  • Data Transfer Rate (Maximum)
    • Thunderbolt 3 : 40 Gb/s (or 5000 MB/s)
  • RAID Capable
    • Yes
  • RAID Levels Supported
    • RAID 0
    • RAID 1
    • RAID 4
    • RAID 5
    • RAID 10
    • JBOD
    • RAID 6
  • RAID Features
    • Software RAID
  • MTBF (Mean Time Between Failures)
    • Varies depending on drive mechanism installed
  • Contact Start Stops
    • Varies depending on drive mechanism installed
  • Mac OS Compatibility
    • macOS 10.12 Sierra
    • macOS 10.13 High Sierra
    • macOS 10.14 Mojave
    • macOS 10.15 Catalina
    • macOS 11.x Big Sur
  • PC OS Compatibility
    • Windows 10 32-bit Edition
    • Windows 10 64-bit Edition
    • Windows Server 2016
  • Other Requirements
    • When using one or more SSDs with 512 byte sectors, macOS 10.13 or later is required. SoftRAID is compatible with Windows 10, or macOS 10.12 or later. Apple Silicon M1 Macs require macOS 11.3 or later. SoftRAID is licensed per computer. Additional seats available.
  • Host Port Requirements
    • Thunderbolt 3 or later
  • Driver Required
    • No
  • Power Supply
    • External UL-listed universal auto-switching power supply
  • AC Input
    • 100-240V, 50-60Hz, 1-2A
  • DC Output
    • +12V, 6A
  • Wattage
    • 72W Watts
  • External Power Adapter
    • Yes
  • Power Delivery
    • Two Thunderbolt 3 ports with 15W power delivery each.
  • Number of Bays
    • 4
  • Device Ports
    • (2) Thunderbolt 3 (USB-C) Ports
    • (1) DisplayPort Port
  • Cooling
    • (1) 60mm 2,800RPM None cooling fan
  • Security Slot
    • No
  • Power/Activity LED
    • Yes
  • Housing Color
    • Black
  • Housing Material
    • Aluminum
  • Dimensions
    • Height: 6.0 cm (2.4 in)
    • Length: 11.3 cm (4.4 in)
    • Width: 13.6 cm (5.4 in)
  • Weight
    • 800.0 g (1.76 lbs)
  • Ambient Temperature
    • Operating: 32°F to 104°F (0°C to 40°C)
    • Non-Operating: -4°F to 158°F (-20°C to 70°C)
  • Altitude
    • Operating: -304.8 m to 3,048.0 m (-1,000 ft to 10,000 ft)
    • Non-Operating: -304.8 m to 12,192.0 m (-1,000 ft to 40,000 ft)


  • Maximum single drive performance is 817 MB/s Reads and 711MB/s Writes due to the bandwidth of the 1X PCIe3.0 bus.
  • Hynix Gold P31 and Samsung PM981a SSD’s are only compatible with Windows 10 when installed in this enclosure.
  • Does not support Dual-Mode DisplayPort (DP++), however it does support Multi-Stream Transport (MST) in Windows 10.
Manufacturer provided specifications for OWC p/n OWCTB3EX4M2SL



  • (1) OWC Express 4M2 SSD Enclosure
  • (1) Power Supply and Power Cable
  • (1) Thunderbolt 3 Cable
  • (1) Quick Start Guide
  • (1) SoftRAID XT
  • (1) SoftRAID XT Quick Start Guide (download only)
  • 1 Year OWC Limited Warranty


Customer Ratings

Write a Review 3.8 / 5 12 out of 18 (67%) reviewers would recommend this product
Verified Buyer
Reviewer: GentleElk-59856
Rating: 3/5 It's ok October 14, 2021 The fine print at the bottom says: Maximum single drive performance is 817 MB/s Reads and 711MB/s Writes due to the bandwidth of the 1X PCIe3.0 bus. Have I seen that I would have purchase something else.

This review is from (*) OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure with SoftRAID.

Response from OWC, Support October 15, 2021 Thank you for the review. The OWC Express 4M2 is a 4 slot NVMe enclosure, and for mind bending performance up to 2800MB/s, the drives would need to be in a raid configuration. Please feel free to contact us at 1-800-275-4576 to discuss return options if you're not satisfied with your purchase.
Verified Buyer
Reviewer: AnxiousOx-14329
Rating: 5/5 It run whit out a glitch since it started. September 25, 2021 I was able to recuperate not only the devices themselves but also all that was drives that were install in a MacPro before.

I would recommend this item to a friend! This review is from OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Verified Buyer
Reviewer: NiceBat-86168
Rating: 5/5 Fast, solid, well made September 10, 2021 With 4x 2TB Gen 3 NVMe's it just screams! Works as advertised.

I would recommend this item to a friend! This review is from OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Response from OWC, Support September 13, 2021 Thank you for your awesome review! We are thrilled to hear that you are enjoying your new Express 4M2 SSD Enclosure!
Verified Buyer
Reviewer: ToughPiranha-96646
Rating: 5/5 Great for sample libraries August 27, 2021 Using this as a high speed sample drive for music composition. I'm only using it plugged into Thunderbolt 2 as of now (Mac Pro '13) and it's still plenty fast for my needs.

I would recommend this item to a friend! This review is from OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Response from OWC, Support August 30, 2021 Thank you for providing us with your feedback! Please feel free to reach out to our support team if further assistance is needed.
Verified Buyer
Reviewer: StormyWoodchuck-91541
Rating: 4/5 My only compliant is the fan is a little loud August 26, 2021 In terms of "bang for your buck" with external data storage you would be hard pressed to find a better product. I would have rated it five stars, but the fan noise is a little loud. All in all, pretty darn good.

I would recommend this item to a friend!

Response from OWC, Support August 27, 2021 Thanks for the recomendation and we appreciate your feedback! Enjoy the storage speed and come back anytime you have more Mac questions!
Verified Buyer
Reviewer: markbuse-72320
Rating: 3/5 Much slower than advertised with non-RAID throughput of 750Mbps or less. July 21, 2021 Due to limitations in the way PCIexpress and Thunderbolt-3 are implemented in the enclosure, the throughput available on high-end NVMe modules is wasted because apparently only ONE of the four PCIexpress lanes is allocated to each individual module. That means a maximum throughput of only 750Mbps from any one module. In practice, this is rarely a problem because the modules themselves are usually unable to maintain a sustained data transfer rate that high anyway. What OWC should disclose is that only through optional software RAID can the full throughput if their enclosures be used. That's not the same as hardware-aggregated throughput that's not dependent on software, which now has a history of intermittent MacOS incompatibility. The cooling fan is also a major disappointment. It ought to be upgraded to a large fan with better bearings to make it quieter and better cool the outer two NVMe modules. Only the two center modules are in the direct path of the fan air flow. Hot air outlets for the enclosure are also inadequate and only at one end. There is no room for heat sinks on the NVMe modules even though some brands will still overheat in this enclosure and quit working. For example, a Crucial 2TB module has shut itself down entirely in the middle of rendering a 4K video. Inland 2TB modules perform very poorly in this enclosure as well with sustained transfer of only 30Mbps. Samsung 2TB 970's perform well.

I would recommend this item to a friend! This review is from OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Verified Buyer
Reviewer: FamousMink-56155
Rating: 2/5 Super noisy June 26, 2021 Every worked fine but the fan noise was bothersome to me.

This review is from (*) OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Verified Buyer
Reviewer: LuckySalmon-70348
Rating: 4/5 Nice form factor and build quality, could use a quieter fan. April 30, 2021 Small convenient form factor. Fan is more noisy than I hoped, but it is easily removed leaving enough room for SSD heat sinks. The result is a silent disk array. As improvement it night be nice to have a version with a heat sink/pipe instead of a fan.

I would recommend this item to a friend! This review is from OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure.

Verified Buyer
Reviewer: PowerfulTurtle-15728
Rating: 3/5 It sounds like a vacuum cleaner April 27, 2021 It's extremely noisy - fast, but irritatingly noisy

Verified Buyer
Reviewer: GentleSwan-36713
Rating: 2/5 Fan makes a horrible grating noise April 26, 2021 I purchased the OWC Express 4M2 to replace an internal RAID controller (just for the sake of some portability). Shipping was quick, so kudos to MacSales for that, at least. But the unit itself lasted about a month before it started making an awful grinding sound. I opened it up, and it was pretty obviously the fan. In the end, I just went back to the internal RAID controller I was using before, and threw away the 4M2. Yes, I could have contacted support and I'm sure they'd have been perfectly friendly and helpful — but I have exactly zero interest in spending my time exchanging emails with support or shipping a defective product back to its manufacturer, then waiting for a new one to arrive.

I wanted an external Thunderbolt enclosure that would last at least a few years. Instead I got one that last a month. And for something as mundane as the fan to be the culprit is really disappointing.

Verified Buyer
Reviewer: LongRat-11251
Rating: 5/5 Cutting edge product April 25, 2021 I received a lot of help from OWC to make sure I bought the right type of product I wanted. This drive was easy to set up, fast , rather quiet and tiny footprint on my desk.

I would recommend this item to a friend!

Verified Buyer
Reviewer: MagnificentManatee-5026
Rating: 5/5 Met Expectations April 24, 2021 Had several emails with sales team. Questions were around the product compatibility with my equipment and the expected speeds I should encounter in the real world.

Happy to report that on my iMac Pro, this unit with 4 sticks of ram and running to soft raid delivered 2200+ speed in a raid0.

Plan is to purchase a 2nd unit and use the Pro version of the Soft Raid in a Raid5 mode across two units and 8 sticks of ram.

Happy with the service and the product. Craig Weatherford.

I would recommend this item to a friend!

Verified Buyer
Reviewer: KL600 Location: Los Angeles Age: 25-34 Experience Level: IT Professional Owned Product: 1-3 months
Rating: 4/5 Best option for remote or travel rig. August 20, 2020 Great enclosure. The only things I didn’t like were the locking screws on the back protrude farther than the actual enclosure, so storage is a pain. Also, my fan was wired incorrectly so I had to reroute the lines on my own. Beware.

I would recommend this item to a friend! This review is from (*) OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure with SoftRAID.

Verified Buyer
Reviewer: PhotoJoseph
Rating: 5/5 So fast. Scary fast. OMG fast. July 30, 2020 What part of the title isn't clear? ;-)

I would recommend this item to a friend!

Verified Buyer
Reviewer: lahzu Location: LA, CA Age: 55-65 Experience Level: Power User Owned Product: less than a month
Rating: 3/5 fast but LOUD! December 9, 2019 I'm an audio engineer, and I bought this to be my primary work drive. Its fan is far too loud in my studio--if this is also your objective, you should look to the (fanless) Thunderblade drives for a more silent solution.

Verified Buyer
Reviewer: SoloRider Location: Swamps of Jersey Age: 45-54 Experience Level: IT Professional Owned Product: less than a month
Rating: 3/5 Meh... not really everything M.2 NVME could be October 17, 2019 I purchased this unit to replace the 2.5 inch drive unit. I had that populated with 2 SSDs and a 2TB Spinning Drive RAID.

On that Thunderbolt 2 Unit I'm able to achieve 325-350 MB/s.

On this new unit, I'm only getting 625-765 MB/s R/W. Kind of a bummer.

I've populated this unit with a 2 TB Samsung 970 EVO Plus Series - 2TB PCIe NVMe - M.2 Internal SSD. I was hoping for near internal drive like performance.

I contact OWC and they said, I need to run this in Raid 0 to get the advertised 2800 MB/s. I guess I should have read the fine print. It will work, but I hoped for better.

Reviewer: Vantage Location: New Jersey Age: 35-44 Experience Level: Power User Owned Product: 1-3 months
Rating: 5/5 Great system! December 18, 2018 I have two volumes running in this enclosure. One is a RAID 0 with two drives. Expect to see around 1400 MB/s with two drives in RAID 0. This runs flawlessly and quiet!

I would recommend this item to a friend!

Reviewer: ivarh Location: Sydney, NSW Age: 45-54 Experience Level: IT Professional Owned Product: less than a month
Rating: 3/5 A great product but with one flaw July 25, 2018 I bought this unit (from a australian reseller) and the setup was easy as. I did however notice one thing that should be in the description for the product.

Each of the 4 m.2 pcnvme slots have only 1 pci express lane. This means that the drive in the slot is limited to 8Gbit transfer speeds.

If you populate all 4 slots and use the included softraid software you will be able to reach the announced speed of 2600Mbyte/sec speed but with fewer drives you will loose out on speed.

As long as you are aware of this individual limitation this is a great unit that gives you heaps of fast storage.

I would recommend this item to a friend!

OWC Express 4M2 4-Slot NVMe M.2 SSD Enclosure with SoftRAID Mfr P/N: TB3EX4M2SL OWC SKU: OWCTB3EX4M2SL Four easy-to-access NVMe M.2 SSD slots customizable for any workflow with up to 32TB of capacity and up to 2800MB/s performance. 1 Year OWC Limited Warranty Ships: Same Day only $349.00
Add to CartOther World Computing TB3EX4M2SL In Stock, Click to Buy Now
Additional Options: DIY Enclosure
  • 0TB
    • Ships: Same Day
    • OWC Price $249.00
DIY Enclosure with SoftRAID XT
  • 0TB