The SY-MRA35030 has been designed to maximize space use by allowing up to four 3.5" SATA III hard drives, while only consuming three 5.25" device bays. The enclosure only requires one molex and one SATA power to power up the four 3.5" hard drives. With the tray-less technology, simply hit the eject button to unlock the access door, allowing the drive to be pulled out of the computer without having to dismount the drive. On the rear of the SY-MRA35030 uses a 80mm cooling fan to pull cool air from the front ventilation slots, over the drives, and exhaust the warm air out through the rear ventilation slots. The enclosure features Intelligent Fan Controller that will alarm the user if the temp reaches 55,60 or 65c