I wanted to replace it with a SSD in my iMac 24 '2009, the SuperDrive. Since I have no 2nd HDD / SSD caddy found, which was explicitly advertised for iMac, I decided for this. He does not quite fit in the plastic CD drive bracket of iMacs. The holes for fastening are slightly offset. You can drill small holes at the corresponding point of the plastic CD drive tray, then hold down the 4 screws the HDD / SSD caddy. The actual installation of the caddy with the drive cage into the Mac went smoothly again.