Unveiled back in 2018, the QNAP TR-004 is finally available for purchase. This storage accessory is a 4-bay hardware RAID storage expansion device that sports USB 3.0 Type-C connectivity and can be attached to a PC or a NAS. When connected to a NAS, the TR-004 can be used as external storage or as an expansion storage device.
https://www.notebookcheck.net/QNAP-launches-the-TR-004-hardware-RAID-storage-expansion-device.400341.0.html