This is a replacement for HP 654540-001 part number to fit a 2.5" SSD/HDD into the 3.5" drive tray. I use this in a HP Z600, but the Z400 and Z800 uses the same tray. It should work in any tray that connects the drive to a fixed backplane.
The design has 3 screw holes instead of the 4 present in the drive bay. Remove the screw from the bay that has no corresponding hole on the design. This should cause no problems, however if you want to be extra careful, use tape to further cement the position of the SSD in the adapter (like I did on one of the photos)