Sonnet's Fusion Flex J3i Mount Lets You Add Up to Three Internal Drives to Your Mac Pro

Sonnet today announced the upcoming launch of its Fusion Flex J3i internal drive mount for the 2019 Mac Pro, which lets users add up to three SATA storage drives to their machines.

sonnet fusion flex installed
Sonnet isn't the only company to launch an internal drive mount for the new ‌Mac Pro‌, and Apple itself sells Promise's Pegasus J2i system that lets you add two drives, but Sonnet says it's the first to let users add three drives right inside the ‌Mac Pro‌ and connected directly via SATA.


The Fusion Flex J3i offers two slots that can accept either 3.5-inch hard disk drives or 2.5-inch SSDs, and a third slot that accepts a 2.5-inch SSD, allowing for a total of 36TB of additional internal storage.

Storage installed via the Fusion Flex J3i won't be as fast as the main NVMe SSDs at the heart of the ‌Mac Pro‌ or PCIe-based storage upgrades, especially if you're using traditional hard disk drives, but if you're a user who wants to prioritize storage space and simplicity over drive speed, Sonnet's Fusion Flex J3i might be worth checking out.

sonnet fusion flex kit
The Fusion Flex J3i includes the mount, required power/data cable assemblies, and mounting brackets to fit 2.5-inch drives into the 3.5-inch drive slots, but the drives themselves are sold separately. It will be priced at $199.99 and launches on June 15.

Related Roundup: Mac Pro
Tag: Sonnet
Buyer's Guide: Mac Pro (Neutral)
Related Forum: Mac Pro

Popular Stories

iphone 17 models

No iPhone 18 Launch This Year, Reports Suggest

Thursday January 1, 2026 8:43 am PST by
Apple is not expected to release a standard iPhone 18 model this year, according to a growing number of reports that suggest the company is planning a significant change to its long-standing annual iPhone launch cycle. Despite the immense success of the iPhone 17 in 2025, the iPhone 18 is not expected to arrive until the spring of 2027, leaving the iPhone 17 in the lineup as the latest...
duolingo ad live activity

Duolingo Used iPhone's Dynamic Island to Display Ads, Violating Apple Design Guidelines

Friday January 2, 2026 1:36 pm PST by
Language learning app Duolingo has apparently been using the iPhone's Live Activity feature to display ads on the Lock Screen and the Dynamic Island, which violates Apple's design guidelines. According to multiple reports on Reddit, the Duolingo app has been displaying an ad for a "Super offer," which is Duolingo's paid subscription option. Apple's guidelines for Live Activity state that...
Low Cost A18 Pro MacBook Feature Pink

Apple's 2026 Low-Cost A18 Pro MacBook: What We Know So Far

Friday January 2, 2026 4:33 pm PST by
Apple is planning to release a low-cost MacBook in 2026, which will apparently compete with more affordable Chromebooks and Windows PCs. Apple's most affordable Mac right now is the $999 MacBook Air, and the upcoming low-cost MacBook is expected to be cheaper. Here's what we know about the low-cost MacBook so far. Size Rumors suggest the low-cost MacBook will have a display that's around 13 ...
govee floor lamp

CES 2026: Govee Announces New Matter-Connected Ceiling and Floor Lights

Sunday January 4, 2026 5:00 am PST by
Govee today introduced three new HomeKit-compatible lighting products, including the Govee Floor Lamp 3, the Govee Ceiling Light Ultra, and the Govee Sky Ceiling Light. The Govee Floor Lamp 3 is the successor to the Floor Lamp 2, and it offers Matter integration with the option to connect to HomeKit. The Floor Lamp 3 offers an upgraded LuminBlend+ lighting system that can reproduce 281...
airpods pro 3 glitter

AirPods New Year's Deals Include Up to $99 Off AirPods Max, AirPods Pro 3, and AirPods 4

Sunday January 4, 2026 8:04 am PST by
Now that the calendar has flipped over into January, steep discounts on popular Apple products have become more rare after the holidays. However, if you didn't get a new pair of AirPods recently and are looking for a model on sale, Amazon does have a few solid second-best prices this week. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a...
Belkin 25W Battery magnetic

CES 2026: Belkin Announces Magnetic Ring Power Bank, Modular Dock, and More

Sunday January 4, 2026 3:02 pm PST by
Belkin today announced a range of new charging and connectivity accessories at CES 2026, expanding its portfolio of products aimed at Apple device users. UltraCharge Pro Power Bank 10K with Magnetic Ring The lineup includes new Qi2 and Qi2.2 wireless chargers, magnetic power banks, a high-capacity laptop battery, and USB-C productivity accessories, with an emphasis on higher charging...
m4 macbook air blue 2

iPadOS and macOS 26.2 Double 5GHz Wi-Fi Bandwidth for Wi-Fi 6E Devices

Monday January 5, 2026 1:57 pm PST by
With the release of iPadOS 26.2 and macOS Tahoe 26.2, Apple has improved the Wi-Fi speeds for select Macs and iPads that support Wi-Fi 6E. Updated Wi-Fi connectivity specifications are listed in Apple's platform deployment guide. The M4 iPad Pro models, M3 iPad Air models, A17 Pro iPad mini, M2 to M5 MacBook Pro models, M2, M3, and M4 MacBook Air models, and other Wi-Fi 6E Macs and iPads now ...
AirPods Pro 3 Year of the Horse Feature

Apple Launches Year of the Horse AirPods Pro 3 for Lunar New Year

Monday January 5, 2026 11:28 am PST by
Apple has designed a limited edition version of the AirPods Pro 3 to celebrate Lunar New Year, and customers in select countries can purchase them starting today. The Year of the Horse Special Edition AirPods Pro 3 feature a unique horse emoji character that's otherwise unavailable. Customers in China, Hong Kong, Taiwan, Malaysia, and Singapore are able to buy the AirPods, and they'll be...

Top Rated Comments

Rychiar Avatar
73 months ago
wait these things don't allow more than one in the first place??
Score: 8 Votes (Like | Disagree)
WildCowboy Avatar
73 months ago

wait these things don't allow more than one in the first place??
The stock storage is either one or two Apple-proprietary storage modules tied to the machine's T2 chip. You can go up to 8TB total with those.

Beyond that, it's either PCIe-based storage, internal SATA like this, or external options.
Score: 8 Votes (Like | Disagree)
Darth Tulhu Avatar
73 months ago
There was a time when I would drool over stuff like this (I still kinda do).

My days of popping the hood are behind me (even though I've been keeping my 2011 17", and 2012 iMac and 15" alive for the last couple of years with those skills).

I'm amazed that we live in an age where I can ACTUALLY replace my hardware with an iPad!

I no longer need the power this machine offers, even if I think it's cool that it can provide it.
Score: 8 Votes (Like | Disagree)
Stang Avatar
73 months ago
$200 for a piece of plastic and 3 sata cables? Yikes.
Score: 8 Votes (Like | Disagree)
SSDGUY Avatar
73 months ago

wait these things don't allow more than one in the first place??
I believe they can take two drives without an expansion mod.
Score: 5 Votes (Like | Disagree)
theluggage Avatar
73 months ago
$200 for a mounting bracket and 2 slightly-customised SATA cables that should have been included with the Mac in the first place...

To be fair, the third cable is a USB3-to-SATA cable which might set you back as much as $7!

Sheesh. I've bought entire PC cases that cost less than $200 and they don't charge extra for the flippin' drive brackets. ...and that's premium Fractal Design/Silverstone stuff that you can compare with Apple and keep a straight face, although the Mac Pro blows right past "premium" and into "over-engineered to the point of parody"...

OK, I know all the big IT firms will charge you $50 for a cable tie if they think you're ordering with a corporate credit card and not watching the price, but that doesn't make it right - and they're usually doing it to compensate for under-bidding on support contracts.


Super weird how the third caddy connects via and internal USB3 cable, rather than SATA like the other two.
...probably because there are only 2 SATA connectors (plus a USB-3) on the Mac Pro mainboard...?
Score: 5 Votes (Like | Disagree)