The OWC MiniStack STX is a storage expansion unit with both Thunderbolt 4 and USB-C connectivity. MiniStack STX has exactly the same dimensions or "footprint" of the Mac Mini and so can be stacked underneath it. You can use the extra storage for large audio and video files, as a RAID using optional OWC SoftRAID software, or as a clone drive.
The STX has enough room inside plus connections for both a single SATA HDD/SSD and NVMe M.2 PCIe SSD. You'll have up to 200 times the storage of the Mac Mini's internal storage plus a built-in Thunderbolt 4 hub with three TB (USB-C) ports and 40GB/sec speed. You can edit 4Kvideo with up to 770MB/sec speed.
My review unit came with just the 2TB of NVMe M.2 SSD ($579 MSRP) and I easily added either a 3.5 or a 2.5-inch hard drive. Besides a TB 4 cable, the kit includes all the hardware to secure either drive size inside. That install process is covered in a video and the instruction manual. It is basic and went without a hitch.
The three Thunderbolt (USB-C) ports enable you to connect to Thunderbolt, USB, and future USB4 drives, displays, A/V mixers, cameras and tablets, a Pro Tools expansion chassis; keyboard, card reader, mouse, or other accessories.
The STX runs super quiet—there is a small fan inside that cools the aluminum case but it never came on during my usage. The MiniStack STX also works well for MacBook and PC notebooks and desktop machines and solves the expansion limitations of new thinner, lighter weight machines.
MSRP prices range from $299 for the DIY empty enclosure model (just the 3-port TB hub) and up to $1,249 for the 18TB model with a 14TB HDD and 4TB SSD.