Device: NexStar MX
In Windows Device Manager, it appears as [USB Attached SCSI (UAS) Mass Storage Device] (without the brackets, obviously). Its hardware IDs are:
According to AIDA64 Extreme, this device is an [ATEC Dual Disk Drive], [Device ID 152D-0561] (without the brackets).
Please note that the first part of that 'device ID' is the vendor ID--152D--which, according to this website, is JMicron Technology Corp., and the second part of that 'device ID' is, well, the device ID 0561. There is another device with the same device ID and that is already in this database: Sharkoon SATA QuickPort. This suggests that these two devices, from two different manufacturers, use the same chip from JMicron, but I'm not positive.
My best guess, after putting all of this information together, is that this device--a Vantec NexStar MX, model NST-225MX-S3--uses a JMicron JMS551 that was sold to, and possibly modified/customized by, ATECH Flash Technology and then sold to Vantec.