This insert guides the drive T5 to the USB plug in the dock slot, as well as supports it while inserted. It is designed to fit snugly into the dock slot so that it doesn't come out while removing the drive. It is taller than the slots in the dock to allow it to be easily removed when desired, and has openings to permit airflow around the drive. Unfortunately, the T5 drive's USB socket is not centered, so the bottom is slightly wider, and the drive may need to be wiggled slightly to get it to mate with the plug.

There is a “T5” on each side to help differentiate T7 slots from T5 slots when installed. In the pictures, this was then painted with an Acrylic paint pen.