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

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 M.2 NVMe SSD slots customizable for any workflow with vibration damping feet that allow for vertical or horizontal orientation. Install up to 16TB 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 levels 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
  • Risk-free: 30-day free trial of fully functional application
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 U.S. based Technical Support.

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 11.0 Big Sur
    • macOS 11.1 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 XT works with macOS 10.12 or later and Windows 10. Intel-based Macs require macOS 10.12 or later. M1 Macs require macOS 11.1 or 11.3 and later. macOS 11.3 is currently available as a public beta.
  • 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)


  • Hynix Gold P31 SSD’s are only compatible with Windows 10 when installed in this enclosure.
  • Does not supoort 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 3.5 / 5 2 out of 4 (50%) reviewers would recommend this product
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 M.2 NVMe SSD Enclosure.

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 M.2 NVMe SSD Enclosure Mfr P/N: TB3EX4M2SL OWC SKU: OWCTB3EX4M2SL Four easy-to-access M.2 NVMe SSD slots customizable for any workflow with up to 16TB 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