StarTech.com 5.25in Trayless Hot Swap Mobile Rack for 3.5in Hard Drive - Internal SATA Backplane Enclosure - Lockable drive bay (HSB100SATBK) : Amazon.co.uk: Computers & Accessories
QNAP 4-bay 1U 12 short-depth rackmount 3.5in SATA HDD USB 3.0 type-C hardware RAID external enclosure - Baechler Informatique
Synology RX418 Drive Enclosure - 1U Rack-mountable - 4 x HDD Supported - 4 x SSD Supported - 4 x Total Bay - 4 x 2.5inch/3.5inch Bay - Serial ATA - eSATA - Cooling Fan - RX418 | Novatech