This is a mount support for dual 2.5in SSD drives. It was specifically modeled to suit an Intel 330 series drive which is a 9mm thick drive.

One of the things that I was pleased about is that it is a tool-less fit for the drives. There are two prominences in the slots to create an interference fit at the screw attachment points. This has worked really well.

In my case this was designed to mount directly to a flat surface.