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

Apple Wallet ID Illinois

Apple Plans to Expand iPhone Driver's Licenses to These 7 U.S. States

Wednesday December 24, 2025 8:40 am PST by
In select U.S. states, residents can add their driver's license or state ID to the Apple Wallet app on the iPhone and Apple Watch, and then use it to display proof of identity or age at select airports and businesses, and in select apps. The feature is currently available in 13 U.S. states and Puerto Rico, and it is expected to launch in at least seven more in the future. To set up the...
iPhone Top Left Hole Punch Face ID Feature Purple

iPhone 18 Pro Launching Next Year With These 12 New Features

Tuesday December 23, 2025 8:36 am PST by
While the iPhone 18 Pro and iPhone 18 Pro Max are not expected to launch for another nine months, there are already plenty of rumors about the devices. Below, we have recapped 12 features rumored for the iPhone 18 Pro models. The same overall design is expected, with 6.3-inch and 6.9-inch display sizes, and a "plateau" housing three rear cameras Under-screen Face ID Front camera in...
maxresdefault

Where's the New Apple TV?

Monday December 22, 2025 11:30 am PST by
Apple hasn't updated the Apple TV 4K since 2022, and 2025 was supposed to be the year that we got a refresh. There were rumors suggesting Apple would release the new Apple TV before the end of 2025, but it looks like that's not going to happen now. Subscribe to the MacRumors YouTube channel for more videos. Bloomberg's Mark Gurman said several times across 2024 and 2025 that Apple would...
maxresdefault

10 Mac Apps Worth Trying in 2026

Wednesday December 24, 2025 9:27 am PST by
2026 is almost upon us, and a new year is a good time to try out some new apps. We've rounded up 10 excellent Mac apps that are worth checking out. Subscribe to the MacRumors YouTube channel for more videos. Alt-Tab (Free) - Alt-Tab brings a Windows-style alt + tab thumbnail preview option to the Mac. You can see a full window preview of open apps and app windows. One Thing (Free) -...
iOS 26

iOS 26.2 Adds These 8 New Features to Your iPhone

Monday December 22, 2025 8:47 am PST by
Earlier this month, Apple released iOS 26.2, following more than a month of beta testing. It is a big update, with many new features and changes for iPhones. iOS 26.2 adds a Liquid Glass slider for the Lock Screen's clock, offline lyrics in Apple Music, and more. Below, we have highlighted a total of eight new features. Liquid Glass Slider on Lock Screen A new slider in the Lock...
iPhone Fold Vertical Feature

Why Apple's Foldable iPhone May Be Smaller Than Expected

Tuesday December 23, 2025 5:21 am PST by
Apple's first foldable iPhone, rumored for release next year, may turn out to be smaller than most people imagine, if a recent report is anything to go by. According to The Information, the outer display on the book-style device will measure just 5.3 inches – that's smaller than the 5.4-inch screen on the ‌iPhone‌ mini, a line Apple discontinued in 2022 due to poor sales. The report has led ...
airpods color prototypes

Apple Tested AirPods in Bright Colors

Saturday December 27, 2025 6:06 am PST by
Apple reportedly tested a version of the first-generation AirPods with bright, iPhone 5c-like colored charging cases. The images, shared by the Apple leaker and prototype collector known as "Kosutami," claim to show first-generation AirPods prototypes with pink and yellow exterior casings. The interior of the charging case and the earbuds themselves remain white. They seem close to some...
Foldable iPhone 2023 Feature Iridescent Search

Samsung Developing 'Wide Fold' With iPhone Fold-Like Design Ahead of Apple's 2026 Launch

Tuesday December 23, 2025 11:55 am PST by
Samsung is working on a new foldable smartphone that's wider and shorter than the models that it's released before, according to Korean news site ETNews. The "Wide Fold" will compete with Apple's iPhone Fold that's set to launch in September 2026. Samsung's existing Galaxy Z Fold7 display is 6.5 inches when closed, and 8 inches when open, with a 21:9 aspect ratio when folded and a 20:18...
iPhone SE Cosmopolitan Clean

Apple Discontinued These 25 Products This Year

Wednesday December 24, 2025 7:24 am PST by
With the end of 2025 near, the time has come to look back at the devices and accessories that Apple discontinued throughout the year. Most of the products that were discontinued this year were simply replaced by a new model with an updated chip. However, the iPhone SE line was entirely discontinued when the iPhone 16e launched, and the iPhone Plus line is being phased out. Below, we have...

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)