Epson Epson - Manual (Page 114)

Attaching Mounting Frames to the Drive
If you are installing a 3.5-inch wide drive, you need to attach
mounting frames to it so that the drive fits in a 5.25-inch wide
bay. These frames usually come with your drive.
Follow these steps to attach mounting frames to a drive:
1. Locate the two mounting frames and four screws that came
with the drive.
2. As shown below, place a mounting frame on one side of the
drive and align it so that the oval holes in the frame are
positioned over the holes in the drive. Then secure the
mounting frame to the drive with the two screws.
3. Repeat step 2 to attach a mounting frame to the other side of
the drive.
5-16 Installing and Removing Slimline Drives