5.25" To 3.5" 2.5" Hdd/Ssd Floppy-Drive Bay ray Bracket Mounting HDD Adapter SSD Hard Drive Supports up to 6*2.5" hard drives - AliExpress
Hard disk drive - Wikipedia
Amazon.com: 5.25'' to 3.5''/ 2.5'' Bay Adapter 5.25" FloppyDrive to Dual 2.5 x 3.5 HDD/SSD Bay Cover Computer Mounting Bracket Kit Supports 7mm 15mm 2.5inch HDD for PC. : Electronics
Axagon ADSA-1S6 USB 3.0 - 2.5" HDD SATA - PlayGoSmart