The SY-MRA35029 has been designed to maximize space use by allowing up to 3 3.5” SATA III hard drives, while only consuming two 5.25” device bays. The enclosure only requires one molex and one SATA power to power up the three 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-MRA35029 uses a 60mm 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- Fits three 3.5 SATA & SAS Drives and takes two empty 5.25" bay slot- Tool-free and tray-less design; it applies patent NSS connector for 50,000 hot-swap cycles guaranteed- 6x6 cm fan to enhance heat dissipation- Intelligent temperature control design; special firmware to control the fan- Independent power control switch and LED indicator- Dual alarm system: buzzer and light indicator- Completely watch over the working status and secure the data safely