For DELL 3.5" to 2.5" SSD HDD Caddy Adapter Tray with. (It is possible to actually fit two 2.5" drives to this caddy - although there are only four screws included). This caddy enables a 2.5" hard drive (either Solid State, SATA or PATA ) to be fitted into a 3.5" drive bay.
eBay