The AS4004T is pretty compact for a 4-bay NAS, measuring 230 x 174 x 170mm (D x W x H). Being cloaked in the latest Asustor diamond-cut exterior design, it's also a stylish looking little black box.
Most of the front bezel is the cover for the four vertically mounted drive bays. This cover is held on by four small magnets making very quick and easy to access the drives. To the left of the cover sits the power button and the LED indicators. From top to bottom these are; power, system status, network (glows blue for 1GbE, purple for 10GbE), USB and finally four displaying hard drive activity/status. Below these sits the One Touch copy button for the front USB 3.1 port that sits towards the bottom of this front side of the NAS.
The rear panel of the NAS is dominated by the grill for the 120mm cooling fan. To the right of this are all the ports; dual 1GbE, single 10GbE and a single USB 3.1 port.
The drive trays are tool free but there are no physical locks on the drive tray doors. The AS4004T supports hot swapping drives.
The AS4004T uses a tool free system to hold the hard drives in place. Two plastic strips with built-in pins fit into the sides of the drive tray with the pins pushing through a vibration deadening grommet into the hard drive sides. It's simple but very effective.