This shot is looking closer at the rear exhaust fan.
Looking closer at the expansion slots, we see that they are slotted to allow for more ventilation.
Moving around to the right side we can see the locks that keep the different sections locked as well as keeping the right side panel locked in place.
The locks themselves are very sturdy. The labels are painted on rather than stickers so they should last a long time and not come off too easily.
The right side panel is also held in place with two thumbscrews in addition to the locks.